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Trades Math Practice Test and Review This material is intended as a review only. To help prepare for the assessment, the following resources are also available: 1. online review material (free of charge) www.viu.ca/assessments 2. A 2.5 hour assessment preparation workshop ($25 per person) www.viu.ca/assessments 3. Up to one month of individualized instruction through the Adult Basic Education Learning Centre. Must have a VIU student number. ($20 per person) For more information contact: Assessment Services: email [email protected] Tel 250 740 6416 local 6276/2831 Nanaimo ABE Learning Centre: Call (250)740-6425 Cowichan Campus Learning Centre: Call (250) 746-3509 Powell River Campus Learning Centre: Call (604) 485-2878 Preparing for the Trades Math Assessment The Trades Math Assessment will assess your math skills to ensure you are ready for your chosen program. The best way to use this review package is to start with the practice test. Once you have completed and scored the test, you will be able to see where you need to do more study. Go to the appropriate place(s) in the study package and PRACTICE, PRACTICE, PRACTICE! More practice material is available if you click on ‘Additional Online Resources’ The following skills will be covered in the 40-question test. You will need to score 70% or above to successfully complete the assessment (minimum 80% for the Electrical Entry program) **YOU CAN USE A CALCULATOR** Addition, subtraction, multiplication and division (whole numbers and decimals) Converting fractions to decimals (and vice versa) Writing percentages as decimals Tenths/hundredths/thousandths Simple exponents (4² etc.) Simple square roots Percentages (adding and deducting tax) Word problems using ratio/cross-multiplication Converting imperial to metric, km - miles Simple algebra (not for Automotive or Motor and Marine Technicians) Geometry (area, volume, perimeter): o Circles, triangles, cylinders, rectangles, squares o **Please note formulae for circles will be given. Other formulas must be memorized. VIU Trades Math Assessment – Practice Test **Round up to 2 decimal places** 1. Write 3,456,394 in words __________________________________________________________________ 2. 3.5 + 8.09= _______ 3. 3.5 – 0.34= _______ 4. 3.5 x 8.09= _______ 5. 3.5 ÷ 8.09= _______ 6. Write the following as a decimal : 25 hundredths 7. Write ⅓ as a decimal _______ 8. Write 1.35 as a faction _______ 9. Write 18% as a decimal _______ 10. Calculate 7² _______ _______ 11. Calculate 2³ _______ 12. What is the square root of 144? _______ 13. 5 is 20% of what amount? _______ 14. What is 7% of 138? _______ 15. John buys 3 t-shirts for $18.32 each, 1 pair of shorts for $29.99. How much is the total with 6% tax? _______ 16. If Max is paid $795.45 for a 35 hour work week. What is his hourly wage? _______ 17. Use this table to convert the quantities/distances below 1 litre = .26 gallons 1 metre = 39.37 inches 1 kilogram = 2.2 pounds 1 kilometre = .62 mile A. B. C. D. E. F. G. H. 25 km = 15 miles= 93 litres= 5 gallons= 12 pounds (lbs)= 5 kg= 15”= 3’= ______miles ______km ______gallons ______litres ______kg ______pounds ______’ _____” ______” **Question 18 (algebra) is not required for Automotive, HDCT, Welding or Motorcycle and Marine Technician) 18. Find the value of x a) 3x = 25 + 1 _______ b) x/6 = 72 _______ 19. Find the perimeter and area of the following shapes: A. Length of one side = 8 ft. Width of one side = 8 ft. a) Perimeter (of one side of the cube) = __________ b) Area of entire cube = ___________ B. 16’ 25’ 7” 18’ 7” a) Perimeter of full shape = __________ b) Area of full shape = ___________ C. Use the following information to answer this question A 5” a) Area of the circle = ___________ b) Radius of the circle =______________ c) Circumference of the circle = _____________ You have completed the practice test. Review your answers below: Answers: 1. Three million, four hundred and fifty six thousand, three hundred and ninety-four 2. 11.59 3. 2.16 4. 28.315 5. 0.433 6. 0.25 7. 0.278 8. 1 35/100 9. 0.18 10. 49 15. $51.21 16. $22.73 17. a) 15.5 miles b) 24.1 km c) 24.1 gallons d) 19.2 L e) 5.4 kg f) 11 lb g) 1’ 3” h) 36” 11. 8 18. x = 12 19. X = 432 20. A. a) 32 ft C. a) 78.5 sq.in b) 5 “ c) 31.4 “ 12. 12 13. 25 14. 9.66 b) 384 square feet B. a) 125 ft 4“ (1504”) b) 7489’ (89869 sq.in.) WHOLE NUMBERS REVIEW Before studying fractions, you should be familiar with all operations on whole numbers. This work will provide a quick review. Answers are at the end on p.4. 1. ADDITION In addition, remember to begin with the right hand column, and work to the left. e.g. 423 + 134 557 Try these: (a) 19 +2 (b) 345 +123 (c) 951 +111 Remember that when the total of any column is greater than 9, you must carry the left digit in that total to the column to the left. 1 e.g. 437 +126 563 Here is some practice: (d) 489 + 96 (e) 2754 + 1666 (f) 238 + 777 (g) 2. SUBTRACTION Remember to begin at the right hand column and move column by column to the left. e.g. 768 – 15 753 Do these: 1069 + 888 (a) 1349 – 36 (b) 864 – 333 (c) 3834 – 2222 Remember that you should check the accuracy of your answer by adding it to what you took away. If it is correct, your result should be the number you began with. In the example above, 753 + 15 = 768, so we can assume that it is correct. Remember that when a digit in the bottom number is too big to subtract from the digit in the top number, you borrow from the next column in the top number first. 3 1 e.g. You can not subtract 9 from 3, so you borrow 1 ten from the tens column first 43 – 19 24 Try these: (d) 753 – 409 (e) 70 – 18 1. Cross out the 4 in the tens place, and replace it with 3. 2. Borrow 10 from 4 to make 13 in the ones column. 3. Subtract 9 from 13 4. Subtract 1 from 3. (f) 8104 – 1987 (g) 7512 – 943 (h) 1000 – 369 (i) 3084 – 2294 3. MULTIPLICATION Take the time to learn your multiplication tables. That will save you a lot of time later on! Multiply each digit in the top number by the bottom number. Write the answer from right to left, starting in the ones column. e.g. 12 41 x4 x 9 Remember that any number multiplied by 0 is 0. 48 369 Try these: (a) 430 x 3 (b) 702 x 41 (c) 3011 x 7 When you multiply by a two or three digit number, be sure to begin your answer under the ones column. Then continue on the line below the tens and then the hundreds. Always multiply from right to left. Leave a space under the bottom digit that has already been multiplied OR add a zero in that space to keep the columns lined up neatly and correctly. Carrying in multiplication is like carrying in addition. Multiply first and then add the number being carried. Line up the digits carefully under the correct column. e.g. 23 x 22 46 46_ 506 638 x 51 638 31900 32538 405 x 266 2430 24300 81000 107730 Now try these: (d) 789 x 46 (e) 5106 x 203 When you multiply by 10, 100, 1000, etc, add the same number of zeroes to the right of the number. e.g. 35 x 10 = 350 41 x 100 = 4100 60 x 1000 = 60 000 Tricky! 4. DIVISION You will need your multiplication tables here too! Learn them well! Division is the opposite of multiplication. That helps you to check your division answer. Pay careful attention to lining up digits, as you did in multiplying large numbers, so that you can keep your working straight. Here are the words: 168 (the dividend) divided by 7 (the divisor) is 24 (the quotient) OR 7 into 168 is 24. e.g. 24 7 168 -14 28 -28 0 Step 1: Divide the divisor 7 into 16 = 2. Place the 2 above the 6. Step 2: Multiply 7 x 2 = 14. Place the 14 under the 16. Step 3: Subtract: 16 – 14 = 2. Step 4: Bring down the next number to the right = 8 Step 5: The new number is 28. Step 6: Divide 7 into 28 = 4. Multiply 4 by the divisor 7 and the answer is 28. Step 7: Subtract 28 from 28 = 0. The division is complete. Check: In division, it is easy to check the answer by multiplying your answer (the quotient) the number byanswer (the divisor). Division problems do notbyalways work you out are withdividing an even as in the last example. 24 x 7 = 168 so the answer is likely to be correct. Sometimes there is an amount left over, which is called the remainder. It is placed on the top line with the letter r for remainder and is part of the quotient Try these: 569 r 3 (a) 4 1631 (b) 7 1046 (c) 9 3004 .e.g. 6 3417 – 30 41 – 36 57 – 54 3 When you check your answer for a division problem with a remainder, multiply your answer (the quotient) by the number you are dividing by (the divisor) and add the remainder. When you divide by a double or triple digit number, you need to use another different skill. You need to estimate, which is a process of thoughtful guessing. This takes time and practice. e.g. 223 28 6244 –56 64 – 56 84 – 84 0 Step 1: Think of about how many times 28 goes into 6244. To do that, round 28 to 30 (28 ≈ 30) and divide that into 62. The answer is approximately or close to 2. Step 2: Place 2 above the last digit of 62. Step 3: 2 x 28 (the divisor) = 56. Then 62 – 56 = 6. Step 4: Bring down 4. Estimate how many times 28, ≈ 30, divides into 64 ≈ 2. Place 2 on the top line. Step 5: 2 x 28 = 56. 64 – 56 = 8. Step 6: Bring down 4. Estimate how many times 28, ≈ 30, divides into 84 ≈ 3. Sometimes your estimate is not quite right, but it should only be 1 more or 1 less than the correct number, so the estimate gives a good starting point. Here is an example with a remainder: e.g. 337 r 32 41 13849 – 123 154 –123 319 – 287 32 Try these: (d) 57 3477 Round 41 ≈ 40. Divide 40 into the first part of the number. 40 goes into 138 about 3 times. Place 3 above the last digit of 138. 3 x 41 = 123. Subtract 123 from 138 = 15. Bring down 4. Estimate how many times 41 40 goes into 154 3. Multiply 3 x 41 = 123. 123 from 154 = 31. Bring down 9. Estimate how many times 41 40 goes into 319 7. 7 x 41 = 287. Step 7: 319 – 287 = 32. Divide 41 into 32. It cannot divide, so 32 is the remainder. Step 1: Step 2: Step 3: Step 4: Step 5: Step 6: (e) (f) 36 7601 67 13467 (g) 29 13796 ANSWERS Addition: Subtraction: (a) 21 (a) 1313 (h) 631 Multiplication: (a) 1290 Division: (a) 407 r 3 (b) 468 (b) 531 (i) 790 (b) 28782 (b) 149 r 3 (c) 1062 (c) 1612 (d) 585 (d) 344 (e) 4420 (e) 52 (f) 1015 (f) 6117 (g) 1957 (g) 6569 (c) 21077 (d) 36294 (e) 1036518 (c) 333 r 7 (d) 61 (e) 211 r 5 (f) 201 (g) 475 r 21 FRACTIONS REVIEW A. INTRODUCTION 1. What is a fraction? Fraction = numerator denominator A fraction consists of a numerator (part) on top of a denominator (total) separated by a horizontal line. For example, the fraction of the circle which is shaded is: 2 (parts shaded) 4 (total parts) In the square on the right, the fraction shaded is 3 and 8 the fraction unshaded is 5 8 2. Equivalent Fractions – Multiplying The three circles on the right each have equal parts shaded, yet are represented by different but equal fractions. These fractions, because they are equal, are called equivalent fractions. 2 4 1 2 4 8 Any fraction can be changed into an equivalent fraction by multiplying both the numerator and denominator by the same number 1 x2 2 x2 = 2 4 Similarly 5 x 2 = 10 9 x2 18 or 1 x4 4 = 2 x4 8 so 1 2 4 2 4 8 or 5 x 3 = 15 9 x 3 27 so 5 = 10 = 15 9 18 27 You can see from the above examples that each fraction has an infinite number of fractions that are equivalent to it. 3. Equivalent Fractions – Dividing (Reducing) Equivalent fractions can also be created if both the numerator and denominator can be divided by the same number (a factor) evenly. This process is called “reducing a fraction” by dividing a common factor (a number which divides into both the numerator and denominator evenly). 441 8 4 2 27 9 3 81 9 9 5 5 1 30 5 6 6 2 3 10 2 5 4. Simplifying a Fraction (Reducing to its Lowest Terms) It is usual to reduce a fraction until it can’t be reduced any further. A simplified fraction has no common factors which will divide into both numerator and denominator. Notice that, since 27 and 81 have a common factor of 9, we find that 3 is an equivalent fraction. 9 But this fraction has a factor of 3 common to both numerator and denominator. So, we must reduce this fraction again. It is difficult to see, but if we had known that 27 was a factor (divides into both parts of the fraction evenly), we could have arrived at the answer in one step e.g. 8 8 1 24 8 3 45 15 3 60 15 4 27 9 3 81 9 9 331 9 3 3 27 27 1 81 27 3 5. EXERCISE 1: Introduction to Fractions a) Find the missing part of these equivalent fractions 1) 2 = 6 3 2) 3 = 12 4 3) 5 = 8 40 x2 Example: 3 = 10 5 x2 4) 1 = 32 16 5) 2 = 45 15 7) 7 = 100 10 8) 3 = 44 4 6.) 7 = 27 9 Since 5 x 2 = 10, multiply the numerator by 2, also. So, 3 = 6 5 10 b) Find the missing part of these equivalent fractions. ÷5 1) 8 = 4 16 2) 24 = 27 9 Example: 5 = 2 10 ÷5 3) 6 = 10 5 4) 25 = 7 35 5) 20 = 6 30 6) 90 = 50 100 Since 10 ÷ 5 = 2 divide the numerator by 5, also. So, c) Simplify the following fractions (reduce to lowest terms). 1) 9 12 5) 20 25 8 12 6) 14 21 2) 6 8 7) 8 16 3) 4) 15 20 8) 24 36 5 = 1 2 10 9) B. 66 99 10) 18 30 TYPES OF FRACTIONS 1. Common Fractions A common fraction is one in which the numerator is less than the denominator (or a fraction which is less than the number 1). A common fraction can also be called a proper fraction. 1, 2 e.g. 3, 4 88 , 8 93 15 are all common fractions. 2. Fractions that are Whole Numbers Some fractions, when reduced, are really whole numbers (1, 2, 3, 4… etc). Whole numbers occur if the denominator divides into the numerator evenly. 8 is the same as 8 ÷ 4 = 2 or 2 4 4 4 1 30 is the same as 30 ÷ 5 = 6 or 6 5 5 5 1 e.g. So, the fraction 30 is really the whole number 6. 5 Notice that a whole number can always be written as a fraction with a denominator of 1. e.g. 3. 10 = 10 1 Mixed Numbers A mixed number is a combination of a whole number and a common fraction. e.g. 23 5 (two and three-fifths) 27 2 (twenty-seven and two-ninths) 9 3 9 = 9 1 (always reduce fractions) 6 2 4. Improper Fractions An improper fraction is one in which the numerator is larger than the denominator. From the circles on the right, we see that 1 3 (mixed number) 4 is the same as 7 (improper fraction). 4 An improper fraction, like 7 , can be changed to a mixed 4 number by dividing the denominator into the numerator and expressing the remainder (3) as the numerator. 16 = 3 1 5 5 e.g. 29 = 3 5 8 8 1 7 4 3 4 1 = 4 7 4 3 14 = 4 2 3 3 7 4 = = 13 4 A mixed number can be changed to an improper fraction by changing the whole number to a fraction with the same denominator as the common fraction. 2 3 = 10 and 3 5 5 5 13 = 5 10 1 9 = = 90 9 91 9 and 1 9 A simple way to do this is to multiply the whole number by the denominator, and then add the numerator. e.g. 4x95 36 5 45 = = = 41 9 9 9 9 10 x 7 2 70 2 10 2 = = = 72 7 7 7 7 5. Simplifying fractions All types of fractions must always be simplified (reduced to lowest terms). e.g. 6 = 2, 9 3 2 5 = 21, 25 5 27 = 3 = 1 1 18 2 2 Note that many fractions can not be reduced since they have no common factors. e.g. 17 , 4 , 18 21 9 37 6. EXERCISE 2 : Types of Fractions a) Which of the following are common fractions (C), whole numbers (W), mixed numbers (M) or improper fractions (I)? 1) 2 3 2) 3 4 5 3) 7 5 4) 8 8 5) 24 2 6) 5 8 19 7) 2 3 3 8) 25 24 9) 24 25 10) 12 12 4) 12 5 5) 100 99 6) 25 2 3) 8 2 3 4) 11 1 5 5) 9 4 5 6) 4 3 4 3) 2 12 18 4) 5 27 54 5) 25 15 6) 90 12 b) Change the following to mixed numbers: 1) 7 5 2) 18 11 3) 70 61 c) Change the following to improper fractions: 1) 2 1 5 2) 6 3 8 d) Simplify the following fractions: 1) 28 40 2) 80 10 C. COMPARING FRACTIONS In the diagram on the right, it is easy to see that 7 is larger 8 than 3 (since 7 is larger than 3). 8 However, it is not as easy to tell that 7 is larger than 5 . 8 6 In order to compare fractions, we must have the same (common) 7 8 = 3 8 denominators. This process is called “Finding the Least Common Denominator” and is usually abbreviated as finding the LCD or LCM (lowest common multiple). Which is larger: 7 or 5 ? 8 6 In order to compare these fractions, we must change both fractions to equivalent fractions with a common denominator. To do this, take the largest denominator (8) and examine multiples of it, until the other denominator (6) divides into it. Notice that, when we multiply 8 x 3, we get 24, which 6 divides into. Now change the fractions to 24th s. When we change these fractions to equivalent fractions with an LCD of 24, we can easily see that 7 is larger than 5 since 21 is greater than 20 . 24 24 8 6 8x1 = 8 (6 doesn’t divide into 8) 8 x 2 = 16 (6 doesn’t divide into 16) 8 x 3 = 24 LCD x3 x4 x3 x4 7 = 21 5 = 20 24 24 8 6 Which is larger: 4 or 5 ? 9 12 Examine multiples of the larger denominator (12) until the smaller denominator divides into it. This tells us that the LCD is 36. Now, we change each fraction to equivalent fractions with the LCD of 36. x4 4 = 16 9 36 x4 x3 5 = 15 12 36 x3 12 x 1 = 12 12 x 2 = 24 12 x 3 = 36 (LCD) LCD is 36. So, 4 is larger than 5 9 12 __________________________________________________________________________ Which is larger: 4 or 13 or 11 ? 5 12 15 Find the LCD by examining multiples of 15. Notice that, when we multiply 15 x 4, we find that 60 is the number that all denominators divide into. x12 4 = 48 60 5 x12 x4 13 = 52 60 15 x4 So, 11 is the largest fraction. 12 15 15 15 15 x x x x 1 2 3 4 = = = = x5 11 = 55 60 12 x5 15 30 45 60 (LCD) Which is larger: 7 or 13 ? 9 18 Notice that one denominator (9) divides into the other denominator (18). This means that the LCD = 18 and we only have to change one fraction 7 to an equivalent fraction. 9 x2 7 = 14 9 18 x2 So, 7 is larger than 13 9 18 ______________________________________________________ ______________________________________________________ 1. EXERCISE 3: Comparing Fractions Which is the largest fraction? (find LCD first) 1) 7 or 6 13 13 2) 1 9 or 18 10 10 3) 4 or 9 5 10 4) 3 or 5 13 12 5) 5 or 4 8 7 6) 1 or 6 or 7 11 2 12 8) 4 or 5 or 3 8 9 12 9) 1 or 3 4 16 7) 2 or 11 3 15 D. ADDING FRACTIONS There are four main operations that we can do with numbers: addition ( + multiplication ( x ), and division ( ÷ ). In order to add or subtract, fractions must have common denominators. This is not required for multiplication or division. ), subtraction ( – 1. Adding with Common Denominators To add fractions, if the denominators are the same, we simply add the numerators and keep the same denominators. e.g. Add 1 + 2 = 3 4 4 4 1 and 5 12 12 Since the denominators are common, simply add the numerators. Notice that we must reduce the answer, if possible. 1 + 5 = 6 12 12 12 = 1 2 2. Adding When One Denominator is a Multiple of the Other Add 5 2 and 9 27 Notice that the denominators are not common. Also notice that 27 is a multiple of 9 (since 9 x 3 = 27). This means that the LCD = 27 (see the last example in “Comparing Fractions”). 2 + 5 = 6 + 5 27 27 27 9 11 = 27 x3 2 = 6 27 9 x3 ), 3. Adding Any Fraction Add 7 and 13 12 15 We must find a common denominator by examining multiples of the largest denominator. We find that the LCD = 60. Add 1 7 + 13 = 35 + 52 60 60 12 15 87 = 60 = 1 9 20 5 and 2 3 6 8 When adding mixed numbers, add the whole numbers and the fractions separately. Find common denominators and add. + If an improper fraction occurs in the answer, change it to a common fraction by doing the following. 1 5 = 1 20 24 6 2 3 = 2 9 8 24 total equals 3 29 24 29 5 3 = 3+1 24 24 5 = 4 24 4. The Language of Addition 1 + 2 CAN BE WORDED 2 3 1 plus 2 2 3 1 and 2 2 3 addition of 1 and 2 2 3 total of 1 and 2 2 3 1 combined with 2 2 3 sum of 1 and 2 2 3 1 more than (or greater than) 2 2 3 Note: All of these can be worded with the fractions in reverse order: e.g. 2 plus 1 is the same as 1 plus 2 3 2 2 3 5. EXERCISE 4: Adding Fractions a) Add the following: 1) 1 2 + 5 5 2) 4 3 + 5 5 3) 4 2 + 9 9 4) 3 3 3 + + 4 4 4 b) Find the sum of: 1) 2 1 + 3 9 2) 1 3 + 2 8 3) 1 5 + 4 16 4) 2 4 + 3 15 c) Add the following: 1 1 + 4 2 4 2) 9 2 1 + 3 3 6 1 4 + 4 2 5 4) 2 3 1 + 6 4 2 5) 4 1 5 + 6 3 6 6) 6 1 3 + 8 3 4 7) 7 2 4 + 3 5 8) 8 2 1 3 + 6 + 1 3 4 8 1) 3 3) 8 d) Evaluate the following: 1) 2 3 and 3 7 2) total of 3) 1 1 plus 2 5 4) 5) 5 3 combined with 12 8 5 3 and 6 8 3 5 greater than 2 7 6) sum of 1 3 and 6 14 E. SUBTRACTING FRACTIONS 1. Common Fractions As in addition, we must have common denominators in order to subtract. Find the LCD; change the fractions to equivalent fraction with the LCD as the denominator. Then subtract the numerators, but keep the same denominator. 5 3 8 8 = 2 3 3 8 = 2 1 or 8 4 16 9 24 24 7 = 24 2. Mixed Numbers When subtracting whole numbers, subtract the whole numbers, and then subtract the fractions separately. 3 5 3 2 -1 = 2 9 9 9 However, if the common fraction we are subtracting is smaller than the other common fraction, we must borrow the number “1” from the large whole number. i.e. 4 2 7 2 9 =3+ + , or 3 7 7 7 7 3 2 from 6 , first change the common fractions to 3 4 8 9 equivalent fractions with the LCD. Since is smaller than , 12 12 borrow from 6. 4 To subtract 1 6 8 12 8 20 = 5 + = 5 12 12 12 12 6 2 5 9 5 -2 = 3 -2 7 7 7 7 4 = 1 7 2 3 8 9 -1 = 6 -1 3 12 4 12 20 9 = 5 -1 12 12 11 = 4 12 The Language of Subtraction 5 2 CAN BE WORDED 6 3 5 2 minus 6 3 2 minus) 3 (NOT 2 subtracted from 5 3 6 2 5 from 3 6 2 5 less than 3 6 5 2 decreased by or lowered by 6 3 the difference of 5 2 and 6 3 NOTE: Unlike addition, we can not reword the above with the fractions in reverse order: 1 2 2 1 i.e. is NOT the same as 2 3 3 2 ====================================================================== 3. EXERCISE 5: Subtracting Fractions a) Subtract the following: 1) 9 1 12 8 2) 14 1 15 6 4) 7 2 9 3 5) 9 7) 3 5 4 8 8) 3) 2 1 - 6 3 6 5 3 6 8 6) 4 1 1 -1 2 4 3) 5 5 6 - 4 7 7 11 2 12 3 b) Subtract the following: 1) 6 4) 4 1 2 - 2 3 3 3 4 - 1 2) 13 11 12 5) 16 1 3 - 5 4 4 2 3 - 5 3 6) 9 4 1 3 - 4 6 8 c) Find the following: 2 1 decreased by is what? 7 21 1) What is 5 3 minus ? 8 16 2) 3) What is 4 7 less than ? 9 9 4) What is 1 9 from ? 6 24 F. MULTIPLYING FRACTIONS 1. Common Fractions When multiplying fractions, a common denominator is not needed. Simply multiply the numerators and multiply the denominators separately. Sometimes, we can reduce the fractions before multiplying. 2 5 25 10 x = = 3 9 3 9 27 1 3 5 3 3 5 x = = 5 7 7 5 7 1 Any common factor in either numerator can cancel with the same factor in the denominator. Multiply after cancelling (reducing). 1 4 3 43 1 x = = 9 8 98 6 3 Note that any whole number (16) has the number “1” understood in its denominator. 1 2 2 5 5 16 x 16 = = 10 8 8 1 1 If more than two fractions are multiplied, the same principles apply. 2 3 1 2 3 1 x x = = 9 20 4 9 20 4 1 120 2. Mixed Numbers Mixed numbers must be changed to improper fractions before 3 multiplying. Remember that a mixed number (like 2 ) can be 4 changed to an improper fraction by multiplying the whole number (2) by the denominator (4) and then adding the numerator. See page 6 for instructions on changing a mixed number to an improper fraction. 2 5 3 8 11 52 x4 = x 4 11 4 11 = 13 4 3 49 17 x 2 = x 9 7 9 7 119 9 2 or 13 9 = 3. The Language of Multiplication 1 2 x CAN BE WORDED 2 3 1 2 multiplied by 2 3 1 2 by 2 3 1 2 of 2 3 the product of 1 2 and 2 3 NOTE: When multiplying, it doesn’t matter which fraction is first. 1 2 2 1 i.e. x is the same as x 2 3 3 2 ======================================================================= 4. EXERCISE 6: Multiplying Fractions a) Multiply (cancel first, when possible): 1) 2 3 x 3 4 2) 12 8 x 9 16 3) 5 9 x 3 15 4) 2 15 x 5 21 5) 5 48 x 8 125 6) 3 16 9 x x 4 27 16 7) 5 7 16 x x 90 x 20 x 3 4 14 8) 2 10) 18 57 6 8 2 x x x x 19 4 32 9 3 2 15 x 3 21 4 4 x 3 5 7 9) 8 12 1 x 2 25 37 12) 2 11) 1 5 x 6 12 b) Find the following: 1) What is 4) 4 5 of 2 1 7 2 of 45? 3 is what number? 2) 41 5 27 by 14 is what number? 3) What is times ? 9 10 7 5) 1 62 of is what number? 2 63 G. DIVIDING FRACTIONS To divide fractions, we invert (take the reciprocal of) the fraction that we are dividing by, then cancel (reduce), and then multiply. Taking the reciprocal of a fraction involves “flipping” the fraction so that the numerator and denominator switch places. Note that a whole number is really a fraction (e.g. 4 = 4 ). 1 2 3 reciprocal 3 2 8 19 reciprocal 19 8 4 reciprocal 4 1 1. Common Fractions Simply invert (take the reciprocal of) the fractions that we are 8 dividing by ( ). Then cancel and multiply. 9 Note: you can only cancel after the division is changed to a multiplication. 5 8 5 9 45 = = 7 9 7 8 56 9 3 9 32 = =6 16 32 16 3 2. Mixed Numbers As in multiplication, mixed numbers must be changed to improper fractions. 2 1 5 15 1 2 = 3 7 3 7 5 7 = 3 15 7 = 9 3. The Language of Division 1 2 CAN BE WORDED 2 3 1 2 divided by 2 3 2 3 into 1 2 divide 1 2 by 2 3 NOTE: In multiplication, the order of the fractions was not important. 1 2 2 1 i.e. x is the same as x 2 3 3 2 In division, this is not the case. The order of the fractions is important. Consider the following: 1 2 1 3 3 = = 2 3 2 2 4 but 2 1 2 2 4 1 = = =1 3 2 3 1 3 3 ====================================================================== 4. EXERCISE 7: Dividing Fractions a) Divide: 1) 3 9 5 15 2) 3 12 7 5 3) 6 4) 7 14 12 5) 13 39 15 40 6) 3 7) 27 1 8 30 3 7 2 8) 1 1 9 3 10) 2 2 3 3 11 10 15 2 1 9) 4 3 3 2 3 9 3 11 22 b) Find the following: 1) 4 2 divided by 5 5 2) 2 4 divided by 5 5 3) 2 2 by 3 3 5) 4 4 into 1 9 5 6) Divide 4) Divide 1 9 12 into 4 25 1 2 by 4 5 FRACTION REVIEW: Decide which operation ( +, -, x, ) by the wording in the question. Then find the answer. 3 of 40? 5 1 2 3) How much is from ? 2 3 4 2 5) and equals….? 5 3 9 7) What is of 300? 10 3 8 9) from equals….? 4 9 5 21 11) How much is of ? 7 50 3 2 13) of equals….? 4 3 1) What is 2) How much is 4 4) How much is 2 1 from 6 ? 3 5 3 of 21? 7 2 divided by 14 is what number? 3 2 8) What is into 12? 5 2 3 10) What is 1 by 3 3 8? 2 1 4 12) Find the total of and and ? 3 6 9 2 3 14) What is greater than 4 ? 5 5 6) ANSWER KEY – FRACTION REVIEW EXERCISE 1: Introduction to Fractions (Page 3) a) 1) 4 6 2) 9 12 3) 25 40 4) 2 32 5) 6 45 6) 21 27 b) 1) 2 4 2) 8 9 3) 3 5 4) 5 7 5) 4 6 6) 45 50 c) 1) 3 4 2) 2 3 3) 3 4 4) 3 4 5) 4 5 6) 2 3 7) 70 100 8) 33 44 7) 1 2 8) 2 3 9) 2 3 10) 3 5 EXERCISE 2: Types of Fractions (Page 6) a) 1) C 2) M b) 1) 1 c) 1) 11 5 2) d) 1) 7 10 2) 8 2 5 2) 1 3) I 4) W 7 9 2 3) 1 4) 2 61 5 11 51 8 3) 26 3 3) 2 2 3 4) 5) W 5) 1 6) M 8) I 9) C 10) W 1 1 6) 12 99 2 56 5 5) 49 5 1 2 5) 5 2 or 1 3 3 4) 5 7) W 6) 19 4 6) 15 1 or 7 2 2 6) 7 12 EXERCISE 3: Comparing Fractions (Page 9) 1) 7 13 2) 1 9 10 3) 9 10 4) 5 12 5) 5 8 7) 11 15 8) 4 9 9) 1 4 EXERCISE 4: Adding Fractions (Page 12) a) 1) 3 5 2) 7 2 2 or 1 3) 5 3 5 4) 9 1 or 2 4 4 b) 1) 7 9 2) 7 8 4) 14 15 c) 1) 7 3 4 d) 1) 1 2 5 2) 1 21 24 2) 12 3) 5 6 9 16 3) 13 3) 3 10 7 10 4) 9 1 4 5) 11 4) 2 3 14 5) 1 6 19 24 6) 15 6) 1 7 7 7) 8 8) 16 15 24 12 8 21 EXERCISE 5: Subtracting Fractions (Page 14) 5 8 a) 1) b) 1) 3 c) 1) 2) 2 3 7 16 23 30 3) 11 24 4) 1 2 3) 6 7 4) 2 5 21 3) 1 3 4) 2) 7 2) 1 9 5) 3 5 6 1 2 5) 10 11 12 6) 3 1 4 6) 4 19 24 7) 1 8 8) 5 24 EXERCISE 6: Multiplying Fractions (Page 16) a) b) 1 2 2) 2 3 8) 10 9) 130 4 or 6 21 21 1) 30 2) 82 1) 3) 1 3) 4) 2 7 5) 10) 1 3 1 or 1 2 2 4) 1 2 6 25 11) 3 6) 1 4 12) 12 5 or 1 7 7 5) 7) 6000 29 1 or 14 2 2 31 63 EXERCISE 7: Dividing Fractions (Page 18) a) 1) 1 8) 1 b) 1 15 1) 2 2) 5 28 3) 9 1 3 10) 9) 1 2) 1 2 3) 4) 1 24 5) 8 9 6) 4 1 2 7) 27 250 2 3 16 75 4) 2 1 2 1 20 6) 5 8 7 15 6) 1 21 7) 270 1 2 14) 5 5) 4 Fraction Review (Page 19) a) 1) 24 2) 1 8) 30 9) 8 15 5 36 3) 1 6 10) 5 4) 9 5 8 11) 5) 1 3 10 12) 1 5 18 13) 1 4 DECIMAL REVIEW A. INTRODUCTION TO THE DECIMAL SYSTEM The Decimal System is another way of expressing a part of a whole number. A decimal is simply a fraction with a denominator of 10, 100, 1 000 or 10 000 etc. The number of decimal places refers to how many zeros will be in the denominator. Note that the number 5.62 is read as five point six two. The first decimal place refers to tenths The second decimal place refers to hundredths The third decimal place refers to thousandths 3 10 31 2.31 2 100 319 2.319 2 1000 2.3 2 Similarly, six decimal places would be a fraction with a denominator of 1 000 000 (millionths). The most common usage of decimals is in our monetary system where 100 cents (2 decimal places) make up one dollar. For example, $2.41 is really two dollars and forty-one hundredths ( 41 ) of a dollar. 100 Examples: 1. Change 2.30 to a fraction Notice that 2.30 is the same as 2.3 In fact, 2.30 = 2.300 = 2.3000 etc. 2.30 2 2. Change 0.791 to a fraction Notice that 0.791 = .791 The zero in front of the decimal place is not needed. 0.791 3. Change .003 to a fraction Notice that the zeros in this example are important. .003 4. Simplify 0.0024000 Notice that zero at the end or zero as a whole number (to the left of the decimal) is not needed. 0.0024000 .0024 30 3 2 100 10 791 1000 3 1000 B. OPERATIONS WITH DECIMALS 1. Addition: Add $2.50 and $1.35 Place numbers in columns, so that the decimal places are in line. Place the decimal point in the same line for the answer. Now, add as if adding whole numbers. Add 1.3928 and 12.43 and .412 Add zeros to fill in columns. This will not change the value of the number (see examples on previous page.) 2. 1.3928 + 12.4300 + 0.4120 14.2348 Subtraction: Subtract $1.30 from $5.45 Set up columns as in addition, and subtract as if subtracting whole numbers. Calculate 5 minus .2982 Fill in columns with zeros, as in addition. Note the difference in wording in these two examples. 3. $2.50 + $1.35 $3.85 $5.45 - $1.30 $4.15 5.0000 - 0.2982 4.7018 Multiplication: Multiply 2.12 by 4.2 At first, ignore the decimals, and multiply as if calculating 212 x 42. Now, add up the decimal places in both numbers and your answer will have that total number of decimal places. Product of 0.0941 and .02 Multiply. Add enough zeros to show the correct number of decimal places 2.12 (2 places) x 4.2 (1 place) 424 8480 8.904 (3 places) .0941 x .02 .001882 (4 places) (2 places) (total = 6) Multiply .5624 by 1000 Notice .5624 x 1000 = 562.4, so multiplying x 1000 (0 decimal places) is the same as moving the decimal place 3 places (since 1000 has 3 zeros) to the right. Similarly, .58 x 10 = 5.8 5.636 x 10 000 = 56 360 .58 x .1 = .058 .58 x .001 = .00058 Division: Divide 2.322 by .12 The divisor (.12) must be changed to a whole number (12) by moving the decimal point 2 places to the right, in both numbers. In the answer, place the decimal point directly above the numbers. Note that zeros must be added to complete the division. .12 . 2.322 19.35 12 232.20 12 112 108 42 36 60 60 0 .5624 x 1000 562.4000 (4 places) (0 places) (total = 4) or 562.4 Divide .003 into 51 Firstly, notice the difference in wording in these two division questions. Zero must be added to the number 51 in order to move the decimal 3 places to the right. .003 51 17000. 3 51000. 3 21 21 0 Divide 254.25 by 1000 Notice 254.25 ÷ 1000 = .25425. So, dividing by 1000 is the same as moving the decimal 3 places to the left (since 1000 has 3 zeros). 0.25425 1000 254.250 200 0 54 25 50 00 4 250 4 000 2500 2000 5000 5000 0 Similarly, 32.52 ÷ 10 = 3.252 2.6 ÷ 10 000 = .00026 EXERCISE 1: Decimal Operations a) b) c) d) e) Do not use a calculator. Change to fractions: (remember to reduce) 1) 5.8 2) 27.3400 3) 30.02 4) 0.590 Addition: 1) 2.49 + .32 2) 0.042 plus .00982 4) 5) 2.76 more than 8.4590 Subtraction: 1) 2.036 from 4.478 2) 12.258 from 13 4) 5) 19.6 decreased by 5.349 1743.2 + 2.984 + 12.35 0.1002 minus 0.05 Multiplication: 1) .21 by .04 2) .42 x .218 4) Product of .009 and 2.003 5) .25 of 288 6) 9.4325 by 1000 7) 9.4325 by .001 3) 5) 3.075 7.342 and 2 and 7.65 3) 670.1 minus 589.213 3) .75 times 132.786 Division: 1) 248 divided by 0.8 2) 15.47 divided by .091 3) 40.4 into 828.2 4) 0.0338 divided by 1.30 5) .0025 into 1.875 6) 923.56 divided by 1000 7) 923.56 divided by .01 C. CONVERSION AND ROUNDING OFF 1. Converting Decimals to Fractions: When changing decimals to fractions, simply create a fraction with 10, 100, 1000 etc. in the denominator. The number of zeros in the denominator is the same as the number of decimal places. 2. 913 1000 25 1 5.25 5 5 100 4 0.913 Converting Fractions to Decimals: When changing a fraction to a decimal, simply divide the denominator into the numerator. Every time a fraction is changed to a decimal, the division will either stop (as 4 in = 0.8) or the division will go on forever 5 2 by repeating (as in = .6 ). Notice that a 3 repeating decimal is shown by a dot over the number (if only one number repeats) or as a bar (if more than one number repeats, as in 2 = .18 ) 4 = 4 ÷ 5 = 0.8 5 2 = 2 ÷ 3 = 0.666…. = .6 3 2 = 2 ÷ 11 = .1818…. = .18 11 11 3. Repeating Decimals Following is a list of some repeating decimals: 1 1 1 = .3 = .16 .142857 3 6 7 1 .11 or .1 9 5 .55 or .5 9 4. 2 .22 or .2 9 7 .77 or .7 9 2 = .6 3 5 = .83 6 4 .44 or .4 9 8 .88 or .8 9 Rounding off: If we want to divide $2.00 into 3 equal parts, we would want our answer to be to the nearest cent (or nearest hundredth). Since our answer is closer to 67 cents than 66 cents, we would round off our answer to $0.67. When rounding to the nearest thousandth, we want our answer to have 3 decimal places. If the fourth decimal place has a 5 or greater, round up. If less than a 5, do not round up. 0.666…. 3 2.000 2.6549 to nearest thousandth = 2.655 2.6549 to nearest hundredth = 2.65 3.95 to nearest tenth = 4.0 EXERCISE 2: Conversion and Rounding Off a) Change to Fractions: (Remember to reduce whenever possible) 1. 2.591 2. 25.030 3. 50.0250 4. 0.8 b) Change to Decimals: (Do not round off) 1. 6. 7 8 5 12 2. 7. 3 11 5 6 3. 8. 4 9 2 3 4. 9. 3 5 7 2 4 7 2 10. 9 5. c) Round Off: 1. 2.864 to nearest hundredth 2. 35.9649 to nearest thousandth 3. 931.85 to nearest tenth 4. 2.091 to nearest tenth 5. 11.898 to nearest hundredth 6. 12.92 to nearest whole number 7. 11.74235 to nearest thousandth 8. 5 to nearest thousandth 9 9. 7 to nearest hundredth 12 ANSWERS EXERCISE 1: Decimal Operations 4 17 2) 27 a) 1) 5 5 50 3) 30 1 50 4) 59 100 5) 3 3 40 b) 1) 2.81 2) .05182 3) 16.992 4) 1758.534 5) 11.219 c) 1) 2.442 2) .742 3) 80.887 4) .0502 5) 14.251 d) 1) .0084 2) .09156 3) 99.5895 4) .018027 5) 72 3) 20.5 4) .026 5) 750 6) 9432.5 e) 1) 310 7) .0094325 2) 170 6) .92356 7) 92356 EXERCISE 2: Conversion and Rounding Off 591 3 1 2) 25 3) 50 a) 1) 2 1000 100 40 b) 1) .875 c) 2) .27 3) . 4 4) 4 5 4) .6 5) .571428 6) .41 6 7) .8 3 8) . 6 9) 3.5 10) . 2 1) 2.86 2) 35.965 3) 931.9 4) 2.1 5) 11.90 6) 13 7) 11.742 8) .556 9) .58 PERCENT REVIEW The use of percentage is another way of expressing numbers (usually fractions) in such a way as to make comparisons between them more obvious. For instance, if you get 28 out of 40 in test A and 37 out of 50 in Test B, it may not be clear whether you have improved or not. The use of percentage will allow this comparison, because a percent is part of 100. (i.e. a percent is a fraction with a denominator of 100). A. CHANGING % TO FRACTIONS / DECIMALS A percent means a part of 100. For example, if you get 95% on a test, your mark was 95 out of 100. A percent can be changed to a fraction or decimal by simply dividing the percentage number by 100. 1. Changing % to Fractions Divide by 100. (i.e. put the % number over 100 and reduce if necessary) 50% = 50 100 = 1 2 If a decimal appears in the fraction, multiply the fraction by 10, 100, 1000 etc. to produce an equivalent fraction without decimals. 24% = 93% 24 100 26.3% = = 5.55% = = = 93 100 6 25 = 26.3 100 263 1000 5.55 100 x 10 10 100 x 100 555 = 111 10000 2000 2. Changing % to Decimals Simply divide by 100. (i.e. move the decimal 50% = .50 9.23% = .0923 4% = .04 148% = 1.48 point 2 places to the left) or .5 . CHANGING FRACTIONS / DECIMALS TO PERCENTS 1. Changing Fractions to Percent If you get 17 out of 20 on a test, it is convenient to change this mark to a percentage. This means changing 17 17 ? to an equivalent fraction with 100 as denominator (i.e. ). 20 20 100 To change fractions to %, simply multiply the fraction by 100%. 17 17 1700 x 100% = = 85% 20 20 20 1 1 x 100% = 50% 2 2 2 2 x 100% = 66. 6 % 3 3 1 19 19 x 100% = 47 % or 47.5% 40 40 2 Note: The mathematical wording for changing a fraction ( 17 ) to a percent would normally be: 20 17 is what % (out) of 20? or What % is 17 (out) of 20? The word “out” is usually not included. e.g. 19 is what % of 75? What % is 7 of 5? 1 19 19 x 100% = 25 % 75 75 3 7 7 x 100% = 140% 5 5 2. Changing Decimals to Percents To change decimals to percents, simply multiply by 100% (i.e. move the decimal point 2 places to the right.) C. USING PERCENTS .29 = .29 x 100% = 29% .156 = .156 x 100% = 15.6% 1.3 = 1.3 x 100% = 130% When percents are used in calculations, they are first converted to either fractions or decimals. Usually it is more convenient to change % to decimals. 1. Multiplying With Percents If a test mark was 50% and it was out of 40 total marks, what was the test test score? 40 ( total marks ) 50% = 50% x 40 50% = score? So = .5 x 40 = 20 20 marks 40 50% (out) of 40 is what number? What number is 50% (out) of 40? \ To find the test score, or the part, we multiply the % by the total. e.g. 85% of 25 is what number? 85% x 25 = .85 x 25 = 21.25 What number is 30% of 45.37? 30% x = .3 x 45.37 = 13.611 45.37 2. Dividing with Percents If a test mark was 50% and you 50% 20 marks total ? = received a score of 20 marks, what was the test out of? 20 ÷ 50% or 20 1 2 ÷ = 20 ÷ .5 = 40 = x 2 1 = 40 20 50% (out) of what number is 20? So, 50% 20 is 50% (out) of what number? = 20 40 total marks To find the total marks, we divide by the %. e.g. 40% of what number is 25? 25 ÷ 40% = 25 ÷ .40 = 62.5 18 is 75% of what number? 18 ÷ 75% = 18 ÷ .75 = 24 D. SUMMARY AND EXERCISE 1. Three types of Percent Problems In summary, there are three things that we can do with percent. We will use the example on the right side of the page to summarize. 1. Finding % or what % of 40 is 20? 2. Finding the Part or 50% of 40 is what number? 3. Finding the total or 50% of what number is 20? 50% = 20 40 = 50% x 20 ÷ 20 (part ) 40 total 20 40 x 100% = 50% 40 = .5 x 40 = 20 50% = 20 ÷ .5 = 40 d) 45.3% =============================================== 2. EXERCISE: PERCENT PROBLEMS 1. Change to Fractions a) 97% b) 82% c) 150% e) 9.25% f) 40% g) 5 9.37% c) 2% d) 243.9% c) 18 75 d) 1 12 g) 0.865 h) 2.37 2. 1 % 2 Change to Decimals a) 42% e) 0.95% 3. b) Change to % a) e) i) 19 20 5 9 .0092 b) f) j) 2 3 38 40 7 4 4. Finding % a) What % of 72 is 18? c) What % of 30 is 18.5? 5. b) 16 is what % of 80? b) What number is 16.5% of 30.2? b) 18 is 55% of what number? Finding the Part a) 40% of 18 is what number? c) 65% of 15 is what? 6. Finding the Total a) 40% of what number is 12? c) 120 is 150% of what number? 7. Percent Problems Combined a) What % of 25 is 5? b) 70% of 15 is what number? c) 85 is 20% of what number? d) 90 is what % of 55? e) 30% of what number is 80? f) What number is 42% of 50? ANSWERS 97 100 b) 41 50 c) 1 1 2 1. a) 2. a) .42 b) .0937 3. a) 95% b) 66. 6 % or 66 g) 86.5% h) 237% i) .92% 4. a) 25% b) 20% c) 61. 6 % 5. a) 7.2 b) 4.983 c) 9.75 6. a) 30 b) 32.72 c) 80 7. a) 20% b) 10.5 c) 425 c) .02 2 % 3 d) 453 1000 e) 37 400 d) 2.439 e) .0095 c) 24% d) 8. 3 % f) 2 5 e) 55. 5 % j) 175% d) 163. 63 % e) 266. 6 f) 21 g) 11 200 f) 95% EXPONENTS AND ROOTS A. EXPONENTS In math, many symbols have been developed to simplify certain types of number expressions. One of these symbols is the “exponent”. Rule: An exponent indicates how many times a base number is used as a factor. Example: 104 = 10 x 10 x 10 x 10 or (10) (10) (10) (10) 35 = 3 x 3 x 3 x 3 x 3 x2 = (x) (x) The exponent is written smaller and is placed above the base number (the number to be multiplied). The first example can be read “ten exponent four” or “ten to the power of four”. Second and third power have special names: second power is usually called “squared”, and third power is usually called “cubed”. Example: 52 is “five squared” 53 is “five cubed” A simple way to work out exponents is to write the base digit the same number of times as the value of the exponent, and put a multiplication sign between each digit. Example: 45 = 4 x 4 x 4 x 4 x 4 (the exponent is 5, so write 4 five times) = 1024 PRACTICE A: Write as an exponent or power (also called “exponential notation”): 1.) 5 5 5 5 = 2.) 2 2 2 2 2 = 3.) 10 10 = 4.) 6 6 6 = Evaluate the following: 5.) 24 = 6.) 53 = 7.) 34 = 8.) 25 = 9.) 102 = 10.) 17 = B. SQUARE ROOTS Rule: Taking the square root of a number is the reverse of squaring the number. The symbol for square root is 9 (the square root of 9) Example: = 3 because (3)2 = 9 144 (the square root of 144) = 12 because (12)2 = 144 PRACTICE B: Evaluate the following: 1.) 4 = 2.) 1 = 3.) 121 = 4.) 81 = 5.) 100 = 6.) 10000 = ANSWERS Practice A (exponents): 1.) 54 2.) 25 3.) 102 4.) 63 5.) 2 x 2 x 2 x 2 = 16 6.) 5 x 5 x 5 = 125 7.) 3 x 3 x 3 x 3 = 81 8.) 2 x 2 x 2 x 2 x 2 = 32 9.) 10 x 10 = 100 10.) 1 x 1 x 1 x 1 x 1 x 1 x 1 = 1 Practice B (square roots) 1.) 2 6.) 100 2.) 1 3.) 11 4.) 9 5.) 10 BASIC ALGEBRA REVIEW SIGNED NUMBERS In the REAL NUMBER SYSTEM, numbers can be either positive or negative. Positive 5 can be written as: +5, or (+5), or just 5. Negative 5 can be written as: –5, or (–5). ADDING AND SUBTRACTING SIGNED NUMBERS When adding numbers of the same sign, simply put the numbers together and carry the sign. (–4) + (–2) = –6 (–9) – 5 = –14 Note: This reads –9 combined with –5 ( + 4) + ( + 2) = +6 – 4 – 2 = –6 When adding numbers of different signs, take the difference between the two numbers; carry the sign of the number with the largest absolute value. For example: –9 + 2. The difference is 7. Take the sign of the 9. Answer = (–7) 4–2=2 NOTE: These two examples are the same, just switched around. –2 + 4 = 2 –7 + 3 = –4 12 + (–3) = 9 –4 + 4 = 0 These last two examples are important, as we use this concept to isolate variables on one side of the = sign when doing algebra. 4 + (–4) = 0 Practice: 1. 2. 3. 4. 5. –9 + 2 = –3 + (–5) = –6 + (–8) = 14 – 14 = –11 + 11 = Answers: 1. –72. –8 3. –14 4. 0 5. 0 ALGEBRA In basic algebra, letters represent numbers. It is important to collect same letters together when possible. For example: 3x + 2x + 6x should be written as 11x (there are 11 x’s altogether) 5y – 3y should be written as 2y 1x is usually written as x (the 1 is assumed) If you are given the value (number) for the letter, you can substitute that value for the letters to answer the equation. For example: Solve 3x 2 when x4 Simply substitute 4 for the x and solve. 3x + 2 3 (4) + 2 12 + 2 = 14 An equation is solved when the unknown letter is isolated on one side of the equal sign. When isolating x, the equation must be kept balanced. To maintain balance, you must always do the same thing to both sides of the equation. For example: x + 3 = 10 3 is being added to x , so do the opposite to both sides and subtract 3 from both sides to isolate x . On the left side, 3 - 3 is 0, leaving just the x on the left. x + 3 = 10 –3 –3 x = 7 Practice: a) Solve x–6 = 4 6 is being subtracted from x so add 6 to both sides to isolate x . Again, –6 +6 = 0, leaving just x on the left. x–6 = 4 x–6+6 = 4+6 x = 10 b) Solve 4x = 20 x is being multiplied by 4 so the opposite of multiply is divide (by 4) on both sides. 4x = 20 4 x = 20 4 4 x = 5 c) Solve y = 5 6 y is being divided by 6 so the opposite of divide by 6 is multiply by 6 on both sides. y = 5 6 y (6) = 5(6) 6 y = 30 d) Solve 4x + 3x + 2 = 5+4 Collect like terms first! 7x + 2 = 9 Now isolate the x by subtracting 2 from both sides 7x + 2 = 9 7x + 2 – 2 = 9 – 2 7x = 7 Divide by the number of x ’s to isolate the x on the left 7x 7 = 7 7 x = 1 Algebra Practice 1. 2. 3. 4. 5. 6. 7. 8. 3x + 9x – 8x = 7y – 3y + 2y = Z – 3 = 25 3x + 4 = 13 (isolate 3x first) 5x + 6 = 31 (isolate 5x first) 2x + 4 , when x = 3 M – 2s = 40, when M = 4s N 5 = 60 Answers: 1. 2. 3. 4. 5. 6. 7. 8. 4x 6y Z = 28 X=3 X=5 10 M = 20 N = 300 BASIC GEOMETRY PERIMETER OF POLYGONS A polygon is a geometric figure with 3 or more sides. The perimeter of a polygon is the distance around the outside of the figure, or the sum of the length of each of its sides. Sometimes formulae are used in calculating the perimeter to make things easier. The most common formulae used are as follows: Perimeter of a Rectangle or a Parallelogram: P = 2 • (l + w) or P = 2 • l + 2 • w Perimeter of a Square: P=4•s Example 1: Find the perimeter of a rectangle that is 6 mm by 9 mm P = 6 mm + 6 mm + 9 mm + 9mm = 30 mm or P or P = 2 • (l + w) = 2 • (6 mm + 9 mm) = 2 • (15 mm) = 30 mm = 2l + 2w = 2 (9 mm) + 2 (6 mm) = 18 mm + 12 mm = 30 mm Example 2: Find the perimeter of a square with a side that is 10 cm long P = 10 cm + 10 cm + 10 cm + 10 cm = 40 cm or P = 4s = 4 (10 cm) = 40 cm Example 3: Find the perimeter of a parallelogram that has a length of 12m and a width of 5m P = 2 (l + w) = 2 (12 m + 5 m) = 2 (17 m) = 34 m or P or P = 2/ + 2w = 2 (12 m) + 2 (5 m) = 24 m + 10 m = 34 m = 5 m + 12 m + 5 m + 12 m = 34 m Example 4: Find the perimeter of a triangle that has the sides 3 mm, 6.5 mm, and 8.6 mm P = 3 mm + 8.6 mm + 6.5 mm = 18.1 mm PRACTICE Find the perimeter of the following shapes: ANSWERS a) 30 m g) 67.2 ft m) 40.51 cm b) h) n) 17 cm 32.4 m 510 m c) i) 20 m 48 ft d) j) 28 mm 47 ft e) k) 54.8 in 21 km f) l) 44 cm 66.62 ft CIRCLE GEOMETRY – CIRCUMFERENCE Circumference is the name for the perimeter (or distance around the outside) of a circle. In this circle, the centre is Z. A, B, and C are points on the circle. Radius: The distance from the centre of the circle to any point on the circle is called the radius (r). (ZA is a radius. ZB and ZC are too). Diameter: The distance from any point on the circle, passing through the centrepoint and continuing on to the outer edge of the circle (d). (AB is the diameter of the circle to the right.) To find the circumference (or perimeter) of the circle, use one of the following formulae: (1) C = π d OR (2) C = 2π r 22 π is called pi and is about 3.14 or 7 Example A: If the circle has a radius of 5 cm, then (1) C =π d (2) C = 2π r The diameter would be twice the radius The radius is 5 cm (or 5 cm x 2 = 10 cm) So C = (3.14) (10 cm) C = (2) (3.14) (5) C = 31.4 cm. C = 31.4 cm Both formulae work equally well. You may choose either one. Now let's practice: 1. A circle has a diameter of 20 m. What is the circumference? 2. A circle has a radius of 7 km. What is the circumference? 3. Find the circumference for the following circles: a) 1) 3) radius(r) = 14 cm 22 (use π = ) 7 b) diameter (d) = 60 mm c) radius (r) = 15 m ANSWERS C = π d ; C = (3.14)(20); C = 62.8 m 2) C = 2π r; C = (2)(3.14)(7); C = 43.96 km b) C = π d ; C = 3.14(60) = 188.4 mm 22 a) C = 2π r; C = (2) (14) = 88 cm 7 c) C = 2 π r ; C = (2)(3.14)(15); C = 94.2 m AREA OF POLYGONS The area of a polygon is the number of squares (of a particular unit) that it takes to cover the surface of the polygon. Formulae are used to calculate the area. The most common formulae are 1 bh Area of a square = s2 Area of a triangle = b h or 2 2 Area of a rectangle = l w Area of a parallelogram = b h 1 Area of a trapezoid = h (a + b) 2 Example 1: Find the area of a triangle which has a base of 10 mm and a height of 9 mm. 1 bxh 2 1 A= (10 mm x 9 mm) 2 1 A= (90 mm2) 2 A = 45 mm2 bxh 2 10 mm x 9 mm A 2 90 mm 2 A 2 A 45 mm 2 A A= or Example 2: Find the area of a square that has a side with a length of 6 cm. A = s2 A = (6 cm) 2 A = 36 cm2 Example 3: Find the area of a parallelogram that has a base of 21 cm and a height of 13 cm. A=bxh A = (21 cm) x (13 cm) A = 273 cm2 Example 4: Find the area of the trapezoid below 1 h (a + b) 2 1 A= (29 m) (66 m + 63 m) 2 1 A= (29 m) (129 m) 2 A = 1870.5 m 2 A= *Notice that units in the answers are units2 (squared) PRACTICE Find the area of the following shapes: a) b) c) 5 cm 12.6 m 10 cm 5 cm 3 cm d) e) f) 14 mm 1 cm 12.2 km 11 cm 24 mm g) 8.6 km h) 2.3 ft i) 12.3 yd 12 ft 10 ft 4 ft Note: There are no diagrams for j) to m). j) A square 35 ft on a side. k) A parallelogram with height of 14 in. and base 23 in. l) A rectangle with length of 8.8 m and width of 4.2 m. m) A triangle with height of 9 km and base of 5.2 km. ANSWERS 2 b) 25 cm 2 c) 158.76 m2 d) 336 mm2 e) 11 cm2 44 ft2 i) 151.29 yd2 j) 1225 ft2 a) 15 cm f) 52.46 km2 g) 5.29 ft2 h) k) 322 in2 l) 36.96 m2 m) 23.4 km2 CIRCLE GEOMETRY – AREA To find the area of a circle, use the formula A =π r 2 Where A = area of the circle: π = pi 3.14 or r 22 7 = the radius of the circle so A=πr2 A = 3.14 x (10)2 A = 3.14 x 100 A = 314 cm2 *notice: answers are units2 r = the radius of the circle = 10 cm Now let’s practice: A: Find the circumference and the area of the following circles: (1) the radius = 4 km (2) the diameter = 10 m B: Find the circumference and the area of the following circles: (1) the radius = 14 in. (2) the diameter = 20 mm ANSWERS A: 1) 2) B: 3) 4) C = 2π r; C = 2 (3.14)(4): C = 25.12 km C= π d ; C = (3.14)(10); C = 31.4m C = 2 π r; C = 2( 3.14)( 14) = 87.92 in C= π d ; C = (3.14)(20) = 62.8 mm A=πr2 A=πr2 A = π r2 A=πr2 A = (3.14)( 4)2 = 50.24 km2 A = (3.14)(5)2 = 78.5 m2 A = (3.14)(14)2 = 615.44 in 2 A = (3.14)(10)2 = 314 mm 2 LINEAR MEASURES : THE METRIC SYSTEM The metric system is used in most countries of the world, and the United States is now making greater use of it as well. The metric system does not use inches, feet, pounds, and so on, although units for time and electricity are the same as those you use now. An advantage of the metric system is that it is easier to convert from one unit to another. That is because the metric system is based on the number 10. The basic unit of length is the metre. It is just over a yard. In fact, 1 metre ≈ 1.1yd. (comparative sizes are shown) 1 Metre 1 Yard The other units of length are multiples of the length of a metre: 10 times a metre, 100 times a metre, 1000 times a metre, and so on, or fractions of a metre: 1 1 1 of a metre, of a metre, of a metre, and so on. 10 100 1000 Metric Units of Length 1 kilometre (km) = 1000 metres (m) 1 hectometre (hm) = 100 metres (m) 1 dekametre = 10 metres (m) (dam) dam and dm are not used 1 metre (m) much. 1 decimetre (dm) = 1 centimetre (cm) = 1 millimetre (mm) = 1 metre (m) 10 1 metre (m) 100 1 metre (m) 10 You should memorize these names and abbreviations. Think of kilo- for 1000, hecto- for 100, and so on. We will use these prefixes when considering units of area, capacity, and mass (weight). THINKING METRIC To familiarize yourself with metric units, consider the following. 1 kilometre (1000 metres) is slightly more than 12 mile (0.6 mi). 1 metre is just over a yard (1.1 yd). 1 centimetre (0.01 metre) is a little more than the width of a paper-clip (about 0.4 inch). 1 cm 1 inch is about 2.54 centimetres 1 millimetre is about the width of a dime The millimetre (mm) is used to measure small distances, especially in industry. 2 mm 3 mm The centimetre (cm) is used for body dimensions and clothing sizes, mostly in places where inches were previously used. 120 cm (47.2 in.) 3 ft 11in. 53 cm 39 cm (20.9 in.) (15.3 in.) The metre (m) is used to measure larger objects (for example, the height of a building) and for shorter distances (for example, the length of a rug) 25 m (82 ft) 3.7 m (12 ft) 2.8 m (9 ft) The kilometre (km) is used to measure longer distances, mostly in situations in which miles were previously used. MENTAL CONVERSION AMONG METRIC UNITS When you change from one unit to another you can move only the decimal point, because the metric system is based on 10. Look at the table below: Units 1000 km 100 hm 10 dam 1 m 0.1 dm 0.01 cm 0.001 mm Example: Complete: 8.42 mm = _______ cm Think: To go from mm to cm will mean I will have fewer cm than mm because cm are larger than mm. So I move the decimal point one place to the left. 8.42 mm 0.842 so, 8.42 mm = 0.842 cm Example: Complete: 1.886 km = _______ cm Think: To go from km to cm means that there will be many more cm than there were km because cm are smaller than km. So I move the decimal place to the right 5 places. 1.886 km 1.88600 so, 1.886 km = 188 600.0 cm Example: Complete: 1 m = _______ cm Think: To go from m to cm … m are bigger, and cm smaller… so, there will be more cm than I started with. I can move the decimal place to the right 2 places. 1 m = 1.00 m 1.00 cm so, 1m = 100 cm Make metric conversions mentally as much as possible. The most commonly used units of metric measurement are: km m cm mm PRACTICE : CONVERTING BETWEEN METRIC UNITS Complete. Do as much as possible mentally. Avoid using a calculator! 1. a) 1 km = _____ m 4. a) 1 dm = _____ m 5. a) 1 cm = _____ m b) 1 m = _____ km b) 1 m = _____ dm b) 1 m = _____ cm 6. a) 1 mm = _____ m b) 1 m = _____ mm 7. 6.7 km = _____ m 8. 9 km = _____ m 9. 98 cm = _____ m 10. 0.233 cm = _____ m 11. 8921 m = _____ km 12. 6770 m = _____ km 13. 56.66 m = _____ km 14. 5.666 m = _____ km 15. 5666 m = _____ cm ANSWERS 1. a) 1. b) 6. a) 6. b) 7. 10. 13. 1000 0.001 0.001 1000 6700 0.00233 0.05666 4. a) 4. b) 0.1 10 5. a) 5. b) 0.01 100 8. 11. 14. 9 000 8.921 0.005666 9. 12. 15. 0.98 6.77 566 600 USING IMPERIAL AND METRIC RULERS We have probably all heard the old saying: “Measure twice; cut once.” Using a ruler efficiently to measure materials and construction is an essential aspect of carpentry. Many trades use both imperial and metric systems of measurement, so you need to know how to read and use both types of rulers and tapes. Often both systems are on the same ruler / tape. This is convenient, but beware of reading the numbers for one system and using the units of measurement for the other. An Imperial ruler, usually 1 foot (ft or ′) long, is divided into inches (″) and parts of inches. An Imperial tape is similarly divided, but is much longer. Many Imperial measures of length divide inches into halves, quarters, eighths, sixteenths - and even thirty-secondths. Metric measures are divided into multiples of 10, starting with millimetres (mms) and centimetres (cms). A 1 metre (m) rule is divided into 100 centimetres or 1 000 millimetres. Here is a quick review of past learning, plus an exercise, using that knowledge, with a ruler and a tape. Practice Exercise 1 2 3 How many of these fractions of an inch are there in one inch? a) quarters b) sixteenths c) halves d) eighths Find the answers to how many a) cms in 3 m b) mms in 55 cms d) cms in 350 mms c) mms in 2 m 5 cms In the boxes below, label the measurements shown on the ruler. Write both numbers and units of either inches (ins or ″) or millimetres / centimetres (mms / cms), whichever is appropriate. You will notice that sometimes the arrow is not exactly on the line of measurement. It is as close as possible. a) e) b) f) c) d) g) h) Practice Exercise Answers 1 a) 4 b) 16 c) 2 d) 8 2 a) 300 cms b) 550 mms c) 2050 mms d) 35 cms 3 a) 1 b) 2 c) d) e) = 2.6 cms f) =2 7 cms or 26 mms 4 6 g) = 13.2 cms h) = 18.9 cms or 132 mms or 189 mms Exercise 1 Label this tape with the measurement points below. Use an arrow and the letter of the measurement point to show your accurate reading. inches mms and cms a) 3 f) 16.6 cms b) 11 cms c) d) e) 4 g) 21.5 cms h) 7 i) 8 j) 18 cm 5 mm Exercise Answers: 1) Arrows are as close as possible. a) e) d) c) b) i) h) f) j) g)