3. 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
4. For example
RED & BLUE Smarties
6 BLUE 3 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”
5. …. Or…
RED & BLUE Smarties
6 BLUE 3 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”
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
7. Try to simplify these
8:2
18:3
4:8
5:25
5:2
4:1
6:1
1:2
1:5
5:2 !!
8. 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
