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Ratio www.mathsrevision.com S4 Simplifying Ratios Ratio Calculations Proportional Division 5-Jul-17 Created by Mr. Lafferty Maths Dept. Starter Questions www.mathsrevision.com S4 5-Jul-17 Created by Mr. Lafferty Maths Dept. Ratio Simplifying a ratio ? www.mathsrevision.com S4 Learning Intention 1. 5-Jul-17 To understand what a ratio is and explain how we can sometimes simplify them. Success Criteria 1. Understand the term ratio. . 2. Calculate and simplify basic ratios. Created by Mr. Lafferty Maths Dept. Ratio Simplifying a ratio ? S4 www.mathsrevision.com Ratios can be used to compare different quantities Example : There are 2 triangles and 3 rectangles. The ratio of triangles to rectangles is said to be 2 : 3 Note: The ratio of rectangles to triangles is said to be 3 : 2 5-Jul-17 Created by Mr. Lafferty Maths Dept. Ratio Simplifying a ratio ? www.mathsrevision.com S4 Simplifying a ratio is like simplifying fractions 6 6 3 Fraction : = ÷2 = 8 8 4 ÷2 Ratio : 5-Jul-17 6: 8 = 6 : 8 =3: 4 ÷2 Created by Mr. Lafferty Maths Dept. ÷2 Ratio Simplifying a ratio ? www.mathsrevision.com S4 Now try Ex 1&2 Ch11 (page 124) 5-Jul-17 Created by Mr. Lafferty Maths Dept. Starter Questions www.mathsrevision.com S4 5-Jul-17 Created by Mr. Lafferty Maths Dept. Ratio Ratio Calculations www.mathsrevision.com S4 Learning Intention 1. To show how to do ratio calculations. Success Criteria 1. Use tabulating method to work out ratios. 2. Show appropriate working. 5-Jul-17 Created by Mr. Lafferty Maths Dept. Ratio Ratio Calculations www.mathsrevision.com S4 Example : The ratio of boys to girls is 4:5. If there are 16 boys, how many girls are there. boys girls x4 5-Jul-17 4 5 16 20 x4 Created by Mr. Lafferty Maths Dept. Ratio Ratio Calculations www.mathsrevision.com S4 Example : The ratio of cars to buses is 3:7. If there are 49 buses, how many cars are there. cars buses x7 5-Jul-17 3 7 21 49 x7 Created by Mr. Lafferty Maths Dept. Ratio Ratio Calculations www.mathsrevision.com S4 Now try Ex 3 Ch11 (page 128) 5-Jul-17 Created by Mr. Lafferty Maths Dept. Starter Questions www.mathsrevision.com S4 5-Jul-17 Created by Mr. Lafferty Maths Dept. Ratio Sharing Money www.mathsrevision.com S4 Learning Intention 1. Explain how to work out proportional division by using shares. Success Criteria 1. Work out equal number of shares for a ratio. 2. Solve problems using shares. 3. Show appropriate working. 5-Jul-17 Created by Mr. Lafferty Maths Dept. Ratio Sharing Money www.mathsrevision.com S4 Example : Step 1 : Bill and Ben share a raffle win of £400 in the ratio 3:5. How much does each get ? Since the ratio is 3:5, there are : 3+5 = 8 shares Step 2 : 50 Each share is worth : 8 400 Step 3 : Bill gets 3 x 50 = £150 Ben gets 5 x 50 = £250 5-Jul-17 Created by Mr. Lafferty Maths Dept. Check ! 150 + 250 = 400 Ratio Sharing Money www.mathsrevision.com S4 Example : Step 1 : Ryan and Ross share 24 cakes in the ratio 3:1. How many cakes does each get ? Since the ratio is 3:1, there are : 3+1 = 4 shares Step 2 : Each share is worth : Step 3 : Ryan gets 3 x 6 = 18 Ross gets 1 x 6 = 6 5-Jul-17 Created by Mr. Lafferty Maths Dept. 6 4 24 Check ! 18 + 6 = 24 Ratio Sharing Money www.mathsrevision.com S4 Now try Exercise 4 Ch11 (page 130) 5-Jul-17 Created by Mr. Lafferty Maths Dept.
