b = number of boys
g = number of girls
The ratio of the number of boys to the number of girls in a class is 5:4 means:
b / g = 5 / 4
Cross multiply
4 b = 5 g
Divide both sides by 5
4 / 5 b = g
g = 4 / 5 b = 0.8 b = 0.8 ∙ 15 = 12
Check results:
b / g = 15 / 12 = 3 ∙ 5 / 3 ∙ 4 = 5 / 4
the ratio of the number of boys to the number of girls in a class is 5:4. if there are 15 boys, how many girls are there
2 answers
Answer is 12