1. Ratio

2. Ratio? Ratio is a way of comparing two or more quantities E.g. –Number of Red Smarties in a box compared to Blue –Number of girls in a class compared to boys

3. For example RED & BLUE Smarties 6 BLUE3 RED “The Ratio of BLUE to RED Smarties is 6 to 3” Blue : Red 6 : 3 2 : 1 “The Ratio of BLUE to RED Smarties is 2:1”

4. …. Or… RED & BLUE Smarties 6 BLUE3 RED “The Ratio of RED to BLUE Smarties is 3 to 6” Red : Blue 3 : 6 1 : 2 “The Ratio of RED to BLUE Smarties is 1:2” “For every RED Smartie, there are 2 BLUES”

5. Simplifying Ratios In the Smarties example, we changed 6:3 to 2:1 This is called Simplifying a ratio We did it by dividing each number by 3 3 was the largest common factor

6. Try to simplify these 8:2 18:3 4:8 5:25 5:2 4:1 6:1 1:2 1:5 5:2 !!

7. Sharing an amount in a given ratio “Bart and Maggie share a bag of 16 sweets in the ratio 3:1” This means “for every 3 sweets Bart gets, Maggie gets 1” 412

8. … quicker way…. “Bart and Maggie share a bag of 16 sweets in the ratio 3:1” 1 share3 shares Another way to think of this 3:1 is shares Bart gets 3 shares to Maggie’s 1 So there are actually 4 shares 16 sweets shared by 4 16 ÷ 4= 4 in a share 1 x 43 x 4412