Answer: 9 girls
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Work Shown:
B = number of boys
G = number of girls
Ratio of boys to girls is 3:1, so B/G = 3/1 which solves to B = 3G
We have 36 total students, meaning that,
B+G = 36
3G+G = 36 ... replace B with 3G
4G = 36
G = 36/4
G = 9
There are 9 girls in the class
B = 3G
B = 3*9
B = 27
and there are 27 boys leading to a total of B+G = 27+9 = 36, which helps confirm the answer.
Note how the ratio 27:9 reduces to 3:1 when we divide both parts by 3.
