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10 E Chapter SA M PL Positive and negative numbers cyan magenta yellow Y:\HAESE\AUS_06\AUS06_10\211AUS06_10.cdr Thursday, 28 March 2013 9:41:51 AM BRIAN 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 Contents: A Opposites B Combined effects C The number line D Addition and subtraction with negative numbers black AUS_06 212 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) Opening problem In indoor cricket, 5 runs are subtracted when a wicket is lost. Blake had only scored 3 runs when he lost his wicket. Things to think about: a What operation would you need to find Blake’s score? b Is it possible to subtract 5 from 3? c What number can we use to display Blake’s score? d Suppose Blake scored 6 runs on the next ball. What would his new score be? E Suppose Amanda has 5 cupcakes and eats 3 of them. The number of cupcakes remaining is 5 ¡ 3 = 2. SA M PL ? Now suppose Adam has 5 cupcakes, and he wants to eat 7. This is impossible, because once Adam has eaten 5 cupcakes, zero cupcakes remain, and there are no more left to eat. It does not make sense to say the number of cupcakes remaining is 5 ¡ 7 because we cannot have less than zero cupcakes. However, there are many situations where it does make sense to talk about numbers less than zero. For example, suppose the temperature at Cradle Mountain, Tasmania, is 5± C at 8 pm. Between 8 pm and midnight, the temperature falls by 7± C. The temperature at midnight is given by 5 ¡ 7. The answer is less than zero, so we call it a negative number. A OPPOSITES Many mathematical problems use opposites. magenta Y:\HAESE\AUS_06\AUS06_10\212AUS06_10.cdr Wednesday, 20 March 2013 1:06:24 PM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 0 5 95 100 50 75 25 0 5 cyan 25 ² earning money is the opposite of spending money ² going up is the opposite of going down ² getting warmer is the opposite of getting cooler. For example: black AUS_06 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) Example 1 213 Self Tutor Write the opposite of: a winning by 7 points b travelling 10 km north. a The opposite of winning by 7 points is losing by 7 points. b The opposite of travelling 10 km north is travelling 10 km south. Instead of using words to describe opposites, we can use positive and negative numbers. POSITIVE NUMBERS Positive numbers are numbers which are greater than zero. E The positive whole numbers are 1, 2, 3, 4, 5, .... SA M PL They can be written with a positive sign (+) before the number, but we normally see them without the positive sign and assume the number is positive. NEGATIVE NUMBERS Negative numbers are numbers which are less than zero. They are written with a negative sign (¡) before the number. ¡1 is read as “minus one” or “negative one”. The negative whole numbers are ¡1, ¡2, ¡3, ¡4, ¡5, .... WORDS INDICATING POSITIVE AND NEGATIVE Some common uses of positive and negative signs are listed in the table alongside. cyan magenta Y:\HAESE\AUS_06\AUS06_10\213AUS06_10.cdr Wednesday, 20 March 2013 1:07:10 PM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 For example, we could write “a profit of $5” as +5. The opposite statement “a loss of $5” is written as ¡5. black Positive (+) Negative (¡) above over increase profit below under decrease loss right left faster win north east slower lose south west AUS_06 214 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) EXERCISE 10A 1 Write the opposite of: a winning $20 b being 10 minutes early c moving 2 steps to the right d being 6 m above sea level. 2 Copy and complete the following table: Statement Number a losing by 3 points ¡3 b c d e a clock is 5 minutes fast 4 m above the water 2± C below zero an increase of 6 kg Opposite of statement Opposite number 3 If north is the positive direction, write these positions as positive or negative numbers: b 12 km north c 15 km south E a 7 km south Discussion SA M PL 4 If temperatures above zero are positive, write these temperatures as positive or negative numbers: a 7± C below zero b 32± C above zero c 40± C below zero Why do you think we choose: ² north to be positive and south to be negative ² east to be positive and west to be negative? B COMBINED EFFECTS In situations where two things happen in opposite directions, we can use a diagram to help find the combined effect. Example 2 Self Tutor Find the combined effect of travelling: a 5 km north and then 1 km south b 2 km north and then 7 km south. a b 1 km 5 km 2 km N W 4 km E N 7 km 5 km S Y:\HAESE\AUS_06\AUS06_10\214AUS06_10.cdr Thursday, 21 March 2013 10:18:27 AM BRIAN 95 100 50 yellow 75 25 0 5 95 The combined effect is travelling 5 km south. 100 50 75 25 0 5 95 50 75 25 0 5 95 100 50 75 25 0 5 100 magenta E S The combined effect is travelling 4 km north. cyan W black AUS_06 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 215 EXERCISE 10B 1 Henry is travelling in a lift. Find the combined effect of going: a up 3 floors and then down 1 floor b up 4 floors and then down 5 floors c down 2 floors and then up 6 floors d down 3 floors and then down 4 floors e down 8 floors and then up 5 floors. Draw a diagram so you can picture the situation. 2 Find the combined effect of travelling: a 10 km east and then 6 km west b 7 km east and then 9 km west c 4 km west and then 5 km east d 11 km west and then 3 km east. N E W S SA M PL E 3 Boris checks the temperature in his bedroom on a regular basis. Find the combined effect if his bedroom gets: a 5± C warmer, then 2± C cooler b 1± C warmer, then 6± C cooler c 4± C cooler, then 11± C warmer d 8± C cooler, then 7± C warmer. 4 Find the combined effect of: a earning $50 and then spending $20 b earning $5 and then spending $15 c spending $10 and then earning $30 C d spending $40 and then earning $40. THE NUMBER LINE We have seen previously that we can place positive numbers on a number line. 0 +1 +2 +3 +4 +5 We can also place negative numbers on a number line by extending the number line to the left: negative whole numbers The number line continues forever in both directions. positive whole numbers -5 -4 -3 -2 -1 0 1 2 3 4 5 cyan magenta Y:\HAESE\AUS_06\AUS06_10\215AUS06_10.cdr Wednesday, 20 March 2013 1:10:50 PM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 Zero is neither positive nor negative. The negative whole numbers, zero, and the positive whole numbers are together known as the integers. black AUS_06 216 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) In the same way that earning $5 and spending $5 are opposites, we say that +5 and ¡5 are opposites. They are the same distance from 0, but on opposite sides of 0. Example 3 Self Tutor Write the opposite of: a +6 b ¡3 a The opposite of +6 is ¡6. b The opposite of ¡3 is +3. Discussion Does zero have an opposite? E We can use a number line to compare the sizes of different numbers and arrange them in order. SA M PL As you move along the number line from left to right, the numbers increase. The number furthest to the right is the greatest number. numbers increase -6 -5 -4 -3 -2 -1 0 1 2 +2 is greater than ¡3 because it is further to the right on the number line. 3 As you move along the number line from right to left, the numbers decrease in size. The number furthest to the left is the least number. numbers decrease -6 -5 -4 -3 -2 -1 Example 4 0 1 2 ¡5 is less than ¡3 because it is further to the left on the number line. 3 a Place ¡7 and ¡2 on a number line. a Self Tutor b Which of these numbers is larger? -2 -7 -10 -5 0 5 b ¡2 is further to the right on the number line, so ¡2 is larger than ¡7. EXERCISE 10C 1 State whether the following integers are positive, negative, or neither: cyan magenta Y:\HAESE\AUS_06\AUS06_10\216AUS06_10.cdr Wednesday, 20 March 2013 1:11:36 PM BRIAN 95 d +3 h ¡8 100 50 yellow 75 25 0 5 95 100 50 c ¡1 g 9 75 25 0 5 95 100 50 75 25 0 b ¡4 f 0 5 95 100 50 75 25 0 5 a 5 e ¡7 black AUS_06 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 217 2 Write the opposite of: a +7 b ¡1 c 2 d ¡4 e +11 f ¡13 3 Write the values of A, B, C, and D: D B -10 C A -5 0 5 10 4 Place the following numbers on a number line. Use a different number line for each part. a 2, ¡5, 1, ¡3 c ¡2, 0, 7, ¡4 b ¡8, 4, ¡1, 6 d ¡9, 3, ¡7, ¡6, 5 5 For each pair of values: i place the values on a number line a 2 and ¡1 ii determine which value is larger. b ¡6 and ¡3 c ¡5 and 3 d ¡5 and ¡8 E 6 Consider the numbers 4, ¡8, 0, ¡2, ¡5, and 1. a Place the numbers on a number line. b Use the number line to write the numbers in order of size, from smallest to largest. SA M PL 7 The table alongside shows the elevation above sea level of various locations. a Place these values on a number line. b Which of these locations are below sea level? c Which of these locations has the: i highest elevation ii lowest elevation? D Location Brisbane Lake Eyre Elevation 15 m ¡16 m Hobart New Orleans, USA 4m ¡2 m Wellington, NZ 3m ADDITION AND SUBTRACTION WITH NEGATIVE NUMBERS We can use a number line to perform additions and subtractions involving negative numbers. ² To increase a number, we move right along the number line. ² To decrease a number, we move left along the number line. Example 5 Self Tutor Use a number line to find: a 5¡8 b ¡7 + 3 magenta -5 -4 -3 -2 -1 0 1 2 3 4 5 yellow Y:\HAESE\AUS_06\AUS06_10\217AUS06_10.cdr Thursday, 21 March 2013 3:37:20 PM BRIAN 95 100 50 75 25 0 5 95 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 a We start at 5, and move 8 units to the left. So, 5 ¡ 8 = ¡3 b We start at ¡7, and move 3 units to the right. So, ¡7 + 3 = ¡4 cyan Subtracting 8 means we decrease the number by 8. We move to the left. black AUS_06 218 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) EXERCISE 10D.1 1 Use a e i a number line to find: 3¡5 b ¡1 + 4 ¡4 ¡ 4 f 7 ¡ 12 1¡9 j ¡5 + 5 2 Use a number line to find: a 2+3¡6 d 3 ¡ 10 + 1 c 0¡6 g ¡3 + 0 k ¡11 + 7 d ¡9 + 2 h ¡8 ¡ 5 l ¡6 ¡ 7 b ¡7 + 4 ¡ 2 e ¡8 + 6 ¡ 7 c ¡5 + 8 + 3 f ¡9 ¡ 5 ¡ 2 Example 6 Self Tutor A lift started 2 floors above ground level. It travelled down 5 floors, then up 1 floor. How many floors above or below ground level is the lift now? E The lift starts at +2 or just 2. We therefore need to find 2 ¡ 5 + 1. Using a number line, 2 ¡ 5 + 1 = ¡2. 0 SA M PL -5 -4 -3 -2 -1 1 2 3 ) the lift is now 2 floors below ground level. 3 A lift started 1 floor below ground level. It travelled 4 floors up, then 6 floors down. How many floors above or below ground level is the lift now? 4 At midnight, the temperature in Canberra was ¡3± C. Between midnight and 9 am, the temperature dropped by 4± C, then rose by 6± C. What was the temperature at 9 am? 5 A football team was 13 points ahead at quarter time. They lost the 2nd quarter by 20 points, won the 3rd quarter by 10 points, and lost the 4th quarter by 7 points. a By how many points was the team winning or losing at: i half time ii three quarter time? b Did the team win or lose the game? By how much? ADDING A NEGATIVE NUMBER Freddy the frog is sitting on the number line. He is performing an addition, so he faces the right. 0 1 2 3 4 5 6 7 8 9 10 DEMO To find 5 + 3, Freddy starts at 5 then hops 3 units forwards, to the right. cyan magenta Y:\HAESE\AUS_06\AUS06_10\218AUS06_10.cdr Wednesday, 20 March 2013 1:18:32 PM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 So, 5 + 3 = 8. black AUS_06 219 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) Freddy can use the same approach to find 5 + ¡3. He again starts at 5, facing the right. To add negative 3, he hops 3 units backwards. He ends up 3 units to the left of his starting point. 0 1 2 3 4 5 6 7 8 9 10 7 8 9 10 So, 5 + ¡3 = 2. Notice also that 5 ¡ 3 = 2. Adding a negative number is the same as subtracting its opposite. For example, 1 + ¡4 is the same as 1 ¡ 4. SUBTRACTING A NEGATIVE NUMBER To perform a subtraction, Freddy faces the left. 0 1 2 3 4 5 6 E To find 7 ¡ 2, Freddy starts at 7 then hops 2 units forwards, to the left. SA M PL So, 7 ¡ 2 = 5. To find 7 ¡ ¡2, Freddy starts at 7, again facing the left. To subtract negative 2, he hops 2 units backwards. He ends up 2 units to the right of his starting point. 0 1 2 3 DEMO 4 5 6 7 8 9 10 So, 7 ¡ ¡2 = 9. Notice also that 7 + 2 = 9. Subtracting a negative number is the same as adding its opposite. For example, 6 ¡ ¡3 is the same as 6 + 3. Example 7 Self Tutor Simplify and then find: a 3 + ¡7 b 3 ¡ ¡7 3 + ¡7 =3¡7 = ¡4 a c ¡3 + ¡7 3 ¡ ¡7 =3+7 = 10 b c ¡3 + ¡7 = ¡3 ¡ 7 = ¡10 d ¡3 ¡ ¡7 d ¡3 ¡ ¡7 = ¡3 + 7 =4 EXERCISE 10D.2 1 Simplify and then find: cyan magenta Y:\HAESE\AUS_06\AUS06_10\219AUS06_10.cdr Wednesday, 20 March 2013 1:19:31 PM BRIAN 95 100 50 yellow 75 25 0 c ¡6 + ¡2 g ¡5 + ¡9 5 95 100 50 75 25 0 5 95 b 6 ¡ ¡2 f 5 ¡ ¡9 100 50 75 25 0 5 95 100 50 75 25 0 5 a 6 + ¡2 e 5 + ¡9 black d ¡6 ¡ ¡2 h ¡5 ¡ ¡9 AUS_06 220 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 2 Simplify and then find: a 10 + ¡4 e ¡9 ¡ ¡6 i ¡4 + ¡5 b 1 ¡ ¡7 f ¡4 + ¡9 j 2 ¡ ¡11 c ¡3 + ¡5 g 0 ¡ ¡5 k ¡3 + ¡4 d ¡8 ¡ ¡14 h ¡11 ¡ ¡18 l ¡12 ¡ ¡4 3 Simplify and then find: a 2 + 7 + ¡3 d ¡3 + ¡8 ¡ ¡5 b 8 ¡ 5 + ¡4 e 7 + ¡11 + ¡1 Example 8 c 10 ¡ ¡6 ¡ 8 f ¡5 + 14 + ¡9 Self Tutor Find the difference between: a 2 and ¡6 b ¡11 and ¡1 The difference between two numbers is the greater number minus the lesser number. SA M PL E a 2 is to the right of ¡6 on the number line, so 2 is greater than ¡6. The difference between 2 and ¡6 = 2 ¡ ¡6 =2+6 =8 b ¡1 is to the right of ¡11 on the number line, so ¡1 is greater than ¡11. The difference between ¡11 and ¡1 = ¡1 ¡ ¡11 = ¡1 + 11 = 10 4 Find the difference between: a 3 and ¡4 d 0 and ¡6 g ¡4 and 10 b ¡7 and 2 e 11 and ¡8 h ¡7 and ¡5 c ¡4 and ¡8 f ¡13 and ¡9 i 5 and ¡7 cyan magenta Y:\HAESE\AUS_06\AUS06_10\220AUS06_10.cdr Thursday, 21 March 2013 10:19:18 AM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 5 A seagull is flying 5 metres above sea level, a kayaker is paddling at sea level, a snorkeller is swimming 2 metres below sea level, and a dolphin is 6 metres below sea level. a Write an integer to describe the height above sea level of each person or animal. b Find the distance between the: i kayaker and the diver ii seagull and the dolphin iii dolphin and the kayaker iv diver and the dolphin. black AUS_06 221 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 6 Write the following statements using directed numbers and calculate the resulting quantity: a b c d e f g spending $50 then spending $40 a fall in temperature of 20± C followed by a rise of 13± C a profit of $310 followed by a loss of $97 a fall in temperature of 5± C followed by a fall of 8± C a journey 21 km north followed by a journey 29 km south winning by 13 points in the 1st half then losing by 17 points in the 2nd half a loss of 3 kg in weight followed by a loss of 2 kg in weight. Team A ¡50 400 900 Team B 810 140 ¡300 E 7 Team A is playing Team B in the card game canasta. This table shows the number of points scored by each team for Hand 1 the first three hands. Hand 2 a Find the difference in points scored by the teams in: Hand 3 i hand 1 ii hand 2 iii hand 3. b Find the total number of points scored by each team so far. SA M PL 8 This table shows the minimum and maximum temperatures in Mount Hotham, Victoria, during a week in July 2012: Minimum temperature Mon ¡5± C Tue ¡2± C Wed ¡3± C Thu ¡7± C Fri ¡5± C Sat ¡4± C Sun ¡3± C Maximum temperature 1± C ¡1± C ¡2± C ¡1± C 1± C 0± C 4± C a Which day had the: i warmest maximum temperature ii coolest maximum temperature iii warmest minimum temperature iv coolest minimum temperature? b Find the difference between the minimum and maximum temperatures on: i Monday ii Thursday iii Saturday. 9 Steve, Paul, Peter, and William played together in the first round of a golf tournament. Each player’s score shows how many shots above or below the ‘par’ score they obtained. In golf, a lower score is better. a Rank these players in order, from best to worst. b Find the difference between: i Steve’s score and Paul’s score ii Paul’s score and Peter’s score. Player Score Steve Paul Peter William +2 ¡3 ¡1 +5 cyan magenta Y:\HAESE\AUS_06\AUS06_10\221AUS06_10.cdr Thursday, 21 March 2013 10:20:21 AM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 c In the next three rounds, William scores ¡4, ¡3, and +1. Find William’s combined score for the tournament. black AUS_06 222 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 10 The children at a party are trying to guess how many lollies are in a jar. The results of the game are shown below. A positive number means that the child guessed too high, and a negative number indicates that the child guessed too low. Child Max Xavier Lauren Molly Result +30 ¡12 ¡4 +21 Claire Jack Gabrielle Luis Kevin +3 ¡24 +9 ¡13 ¡7 a b c d SA M PL E How many children guessed too low? How many children were within 10 of the correct answer? Which child’s guess was the closest? Find the difference between: i Xavier’s guess and Kevin’s guess ii Gabrielle’s guess and Luis’ guess. e Jack’s guess was 50 lollies. i How many lollies were in the jar? ii What was Molly’s guess? Investigation Calculator use We can use our calculator to perform operations with negative numbers. We use the +/¡ or (¡) button to write negative numbers. For example, to find ¡3 ¡ ¡2, press +/¡ 3 ¡ +/¡ 2 = . What to do: 1 Use your calculator to find: a ¡10 + 8 d ¡31 + 49 + ¡60 b 23 ¡ 48 e 19 ¡ ¡83 + ¡43 c ¡57 + 39 f ¡124 + ¡71 ¡ ¡94 cyan magenta yellow Y:\HAESE\AUS_06\AUS06_10\222AUS06_10.cdr Monday, 25 March 2013 8:47:47 AM BRIAN 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 2 Use your calculator to solve the following problems: a Los Angeles has an altitude of 113 m, and the Dead Sea has an altitude of ¡423 m. Find the difference between their altitudes. b Harry’s credit card balance was ¡$347 at the start of the month. During the month he bought a dishwasher for $549, then made a credit card repayment of $250. What is his credit card balance now? black AUS_06 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 223 Game This game can be played by 2 or more people. You will need: Two sets of cards with the numbers ¡15 to 15 written on them (62 cards in total). You can make your own, or print them off by clicking on the icon alongside. ¡15 ¡14 .... ¡1 0 1 .... 14 15 ¡15 ¡14 .... ¡1 0 1 .... 14 15 PRINTABLE CARDS What to do: 1 Shuffle the cards, then deal 6 cards to each player. Place the remaining cards face down in a pile. ¡8 12 ¡4 and 7 SA M PL Examples of sets include E 2 Select a player to go first. The player takes a card from the top of the pile. The player then looks at his cards, and tries to form a set of 3 cards which sum to zero. ¡7 0 . 3 If the player can form a set, the player puts the cards to one side, and then takes another turn. If not, play passes to the next player. 4 Play continues until all of the cards in the pile have been taken. The winner is the player with the most sets. KEY WORDS USED IN THIS CHAPTER ² integer ² number line ² negative number ² opposite ² negative sign ² positive number Review set 10 1 Write the opposite of: a travelling 10 km south b getting 3 cm shorter. 2 Find the values at point A, B, and C. C A -10 -5 0 magenta 10 Y:\HAESE\AUS_06\AUS06_10\223AUS06_10.cdr Wednesday, 20 March 2013 1:30:01 PM BRIAN 95 c ¡5 ¡ 6 f 1¡7+9 100 50 yellow 75 25 0 5 95 b ¡4 + 7 e ¡8 ¡ 3 + 7 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 4 Use a number line to find: a 6 ¡ 10 d 5 ¡ 10 + 3 5 5 a Place the values ¡7 and ¡5 on a number line. b Determine which of the values in a is larger. 3 cyan B black AUS_06 224 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 5 Isabella ran a lemonade stall at a school festival. She made a $10 profit in the first hour, a $25 loss in the second hour, and a $7 profit in the third hour. Find the total profit or loss made by Isabella over the three hours. 6 Simplify and then find: a 3 + ¡8 d 9 + ¡9 b 5 ¡ ¡5 e 11 + ¡7 ¡ ¡1 c ¡6 ¡ ¡13 f 2 + ¡10 ¡ ¡4 Multiple Choice E Practice test 10A 1 What is the combined effect of losing $40 and then winning $30? B losing $20 C losing $10 D winning $10 E winning $70 SA M PL A losing $70 2 Which of the following integers is negative? A 1 B +5 C 0 D ¡3 E 2 3 Which number is indicated by point X on this number line? X -10 -5 A 7 0 B 8 5 C ¡7 10 D ¡9 E ¡8 C 0 D 3 E ¡7 C ¡2 D 4 E 18 4 Which of the following numbers is the largest? cyan magenta 50 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 6 The scores of three contestants at the end of a game show are given alongside. What is the difference between Phil’s score and Janice’s score? A 70 B 15 C 55 D ¡15 E ¡55 yellow Y:\HAESE\AUS_06\AUS06_10\224AUS06_10.cdr Wednesday, 20 March 2013 1:33:56 PM BRIAN PIERRE PHIL JANICE 55 -15 40 95 5 The value of ¡3 ¡ 11 + 10 is: A ¡24 B ¡4 100 B ¡6 75 A 4 black AUS_06 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) Practice test 10B 225 Short response 1 Find the combined effect of: a going up 5 floors and then down 7 floors b travelling 8 km east and then 2 km west c getting 3± C warmer and then 9± C cooler. 2 Write the opposite of: a +5 b ¡8 c 12 3 Place the following numbers on a number line: ¡9, 4, 0, ¡2, 8. 4 Find: a 11 + ¡1 b 3 ¡ ¡9 c ¡10 ¡ ¡10 5 Find the difference between: a 4 and ¡4 b ¡9 and ¡2 d ¡4 + 13 + ¡8 E c ¡3 and 0 SA M PL 6 In a spelling quiz, students were awarded points for answering questions correctly, and they lost points for answering questions incorrectly. Nick scored 7 points, Teresa scored 12 points, and Brett scored ¡4 points. Find the difference between: a Teresa’s score and Brett’s score b Brett’s score and Nick’s score. Practice test 10C Extended response 1 The top of a tree is 5 metres above ground level. A bird in the tree is 3 metres above ground level, the tree’s roots are 1 metre below ground level, and a pipe is 2 metres below ground level. a Write a positive or negative number to describe the height above ground level of each object. b Find the difference in height between the: i tree top and the roots ii bird and the pipe iii roots and the pipe. cyan magenta Y:\HAESE\AUS_06\AUS06_10\225AUS06_10.cdr Wednesday, 20 March 2013 1:42:49 PM BRIAN 95 100 50 yellow 75 25 0 5 95 100 50 75 25 0 5 95 100 50 Find the value of ¡4 + ¡4 + ¡4. Explain why ¡4 + ¡4 + ¡4 is the same as 3 £ ¡4. Use a and b to find the value of 3 £ ¡4. Write a rule which describes how to multiply a positive number by a negative number. Use your rule to find 5 £ ¡7. Use your calculator to check your answer. 75 25 0 a b c d e 5 95 100 50 75 25 0 5 2 black AUS_06 226 POSITIVE AND NEGATIVE NUMBERS (Chapter 10) 3 Suppose A owes B $11, B owes C $13, and C owes A $5. a Use positive and negative numbers to complete this table: Amount B owes A ¡$11 Amount B owes C Amount A owes B $11 Amount A owes C ¡$5 Amount C owes A Amount C owes B b Find the sum of each column to find the total amount owed by: i A ii B iii C. c Explain how all three debts can be repaid in only two payments. Game Lucky Dip Lucky Dip is a game for two people. E How to play: 1 Each player prints a grid like the ones alongside. This sheet represents their Lucky Dip box containing 16 small bags. Each player marks any 3 squares with the numbers 2, 4, and 5. 2 represents a bag containing $2, 4 represents a bag containing $4, and 5 represents a bag containing $5. All the other bags are empty. Joanne A B E F I J M N O D A G H E K L I J M N SA M PL 5 Troy C 2 P 4 4 B F 2 C D G H K L O P 5 2 Players take turns to pick a bag from their opponent’s Lucky Dip box, by calling the letter of a square. 3 If a player does not get a bag containing money, then he or she loses $2. If a bag containing money is selected, then that amount is gained. 4 The player with the most money after 8 rounds each is the winner, unless one player has gained all of the opponent’s money in less than 8 rounds. Each player must have the same number of selections. Sample game: Consider the Lucky Dip boxes for Joanne and Troy above. Joanne Selection Score C ¡2 J ¡4 K ¡6 A ¡2 H 3 N 1 F 3 Round 1 2 3 4 5 6 7 The game ends after 7 rounds, with Joanne winning. PRINTABLE GAME Troy Selection G P L A N M B Score ¡2 2 0 ¡2 ¡4 ¡6 ¡1 cyan magenta yellow Y:\HAESE\AUS_06\AUS06_10\226AUS06_10.cdr Wednesday, 3 April 2013 5:27:10 PM BRIAN 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 95 100 50 75 25 0 5 Print two pages and play against a partner! black AUS_06