Question

The ratio of boys to girls at a college is $4:5$.

How many boys and are there if the total number of students is girls $3321$?

Answer 1

Find the number of boys:

Given the ratio of boys to girls is $4:5$.

So the ratio of boys is $4$, and the ratio of girls is $5$.

Hence total ratio is $4+5=9$.

Given that the number of girls are $3321$.

Apply the ratio formula $\mathrm{Number}\mathrm{of}\mathrm{boys}=\frac{\mathrm{Ratio}\mathrm{of}\mathrm{boys}}{\mathrm{total}\mathrm{ratio}}\times \mathrm{number}\mathrm{of}\mathrm{girls}$.

Substitute the known values:

$\begin{array}{rcl}\mathrm{Number}\mathrm{of}\mathrm{boys}& =& \frac{4}{9}\times 3321\\ & =& 4\times 369\\ & =& 1476\end{array}$

Hence, the number of boys is$1476$.