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Targeting that Grade C in Mathematics A Simplified Revision Guide St Edmund Campion Mathematics Department Adding Fractions: SMILEY FACE 2 7 + 3 4 = 8 + 21 28 = 29 = 1 1 28 28 Fraction of an Amount 1. Divide amount by denominator (bottom) 2. Multiply by the numerator (top) Find ⅚ of £42 Answer: 42 6 × 5 = £35 Percentage Increase/Decrease with a Calculator 1. Divide amount by 100 using your calculator 2. Multiply by the percentage 3. Add or subtract to the original amount depending whether it is an increase or decrease Increase £342 by 19% Answer: 342 100 × 19 = £64.98 £342 + £64.98 = £406.98 Pythagoras’ Theorem 14cm 13cm 17cm 17² + 13² = 458 9cm 14² - 9² = 115 √458 = 21.4cm (3sf) √115 = 10.7cm (3sf) Solving Equations Solve Equations with Unknown on Both Sides Trial & Improvement The question will tell you what 2 values the solution lies between. Always start halfway between the two numbers Estimating Always round the numbers as much as possible so that you make the calculation the easiest it can be. By first rounding each number to 1 significant figure find estimates to the following calculation: 2.8 x 61.59 12.9 ≈ 3 x 60 = 10 It is easier to round 12.9 to 10 instead of 13 180 10 = 18 Straight Line Graphs Percentages without a Calculator 1. Find 10% first by dividing by 10 (take off 0) 2. Then halve to get 5% 3. And halve again to get 2½ % if needed 4. Add answers together to get required percentage Find 15% of £210 Answer: 10% = £21 15% = 21 + 10.50 = £31.50 5% = £10.50 Ratios Make sure you read the question carefully first Divide £120 in the ratio of 5:1 1) 5 + 1 = 6 3) 5 x 20 = £100 2) 120 6 = £20 1 x 20 = £20 Planes of Symmetry The Circle Parts The Circle: Area and Circumference C = πd = 3.14 x 11.2 = 35.2cm (1dp) A = πr² = 3.14 x 5.8 ² = 105.6cm² (1dp) Angle Types Area of Triangle Area = 12 x 8 2 Multiply BUT remember to halve your answer = 48cm² Area of Composite Shape Split into a triangle and a rectangle Area = 6 x 8 2 = 24cm² Total Area = 24 + 60 Area = 6 x 10 = 60cm² = 84cm² Volume of Cuboid Volume of Triangular Prism Multiply the base, height and length together BUT remember to halve as it is triangular Volume = 1.7 x 2.3 x 13 2 = 25.4cm³(1dp) Quadrilaterals: 4 Sides Measuring Angles Drawing Angles Long Multiplication of Decimals Forget about decimal point first, but remember to put it back in the right place at the end. Perpendicular and Angle Bisectors Put compass points at A and B and draw to arcs that cross (zulu shield) 3D Coordinates Always (x, y, z) and start from (0, 0, 0) The questions usually involve a cuboid and you need to identify coordinates U = (4, 7, 0) Q = (4, 0, 0) R = (4, 0, 3) V = (0, 0, 3) T = (0, 7, 0) S = (0, 7, 3) O = (0, 0, 0) Metric and Imperial Units Metric Imperial Metres Yards, Feet Centimetres Inches Kilometres Miles Grams Ounces Kilograms Stone/pounds Litres Gallons Prime Factors: Factor Trees +, + ―> + +, - ―> -, + ―> -, - ―> + nth Term of Sequence 5 12 19 26 33 Difference = 7 0th Term = -2 (this would be the number before the first term So nth term formula is: T(n) = 7n - 2 Averages Mean: Add up the numbers and divide by how many there are Mode: Most common number Median: The middle number Range: The highest value subtract the lowest Pie Charts 360 20 = 18 Multiply all frequencies by 18 Estimated Mean Mean = 4320 120 = 36 1. Find mid points 2. Multiply frequency and midpoints to get fx 3. Add up frequency and fx columns 4. Divide sum of fx column by frequency column to get answer Scattergraphs and Correlation A correlation shows a relationship between the two pieces of data being graphed. There are three types of correlation. x x x x x x x POSITIVE NEGATIVE x x x x NO Correlation Stem and Leaf Diagrams BIDMAS 6 + 4 x 3 20 ― 6 x 3 = = 6 + 12 = 18 20 – 18 = 2 Tesselations A shape tessellates if it fits together without leaving any gaps like a jigsaw. Rotating a Shape 1. Use tracing paper and trace the shape 2. Put pencil at the coordinate 3. Rotate (turn) the shape the number of degrees anticlockwise Translations Factorising Number Factors Letter Factors Look for the largest number that goes into both numbers Look for the common letters Factorise 4a² + 7a Factorise 12a + 15 = 4aa + 7a 3 is the largest number that goes into 12 and 15 12a + 15 = 3(4a + 5) = a(4a + 7) Indices x2 × x4 = x 6 7 3x 5 x x = × 4x² = 9 12x 4 x Substitution Multiplying Fractions 1. Multiply the Numerators (Top numbers) 2. Multiply the denominators (bottom numbers) 3. Simplify your answer 3 x 4 6 7 = 3 x 6 4 x 7 = 18 28 = 9 14 Area, Perimeter and Volume by Counting Perimeter Count the outside of the shape Area Count the squares inside the shape Perimeter = 10cm Volume = 10cm³ Area = 5cm² Volume Count the cubes that make up the shape Frequency Polygons Need to plot the frequency against the mid group value. Can draw the bars in first