Question

The ratio of girls to boys in a school is $2:7$. If the number of boys is $630$, find the number of girls in the school.

Answer 1

Given:
$\frac{\mathrm{no}.\mathrm{of}\mathrm{girls}}{\mathrm{no}.\mathrm{of}\mathrm{boys}}=\frac{2}{7}$
Number of boys = $630$
$\frac{\mathrm{no}.\mathrm{of}\mathrm{girls}}{630}=\frac{2}{7}$
Cross multiply
$7\times \mathrm{no}.\mathrm{of}\mathrm{girls}=2\times 630$
$\mathrm{No}.\mathrm{of}\mathrm{girls}=\frac{2\times 630}{7}$
= $\frac{2\times 7\times 90}{7}=180$
So, the number of girls in the school is $180$.