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Ratio. 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. For example. RED & BLUE Smarties. Blue : Red. 6 : 3. 2 : 1. 6 BLUE. 3 RED.
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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
For example RED & BLUE Smarties Blue : Red 6 : 3 2 : 1 6 BLUE 3 RED “The Ratio of BLUE to RED Smarties is 6 to 3” “The Ratio of BLUE to RED Smarties is 2:1”
…. Or… RED & BLUE Smarties Red : Blue 3 : 6 “For every RED Smartie, there are 2 BLUES” 1 : 2 6 BLUE 3 RED “The Ratio of RED to BLUE Smarties is 1:2” “The Ratio of RED to BLUE Smarties is 3 to 6”
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
Try to simplify these 8:2 18:3 4:8 5:25 5:2 4:1 6:1 1:2 1:5 5:2 !!
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” 4 12
“Bart and Maggie share a bag of 16 sweets in the ratio 3:1” … quicker way…. 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 4 1 share 4 3 x 4 3 shares 12