To solve this problem, we need to find the number of boys in the school given the ratio of boys to girls and the number of girls.
The ratio of boys to girls in the school is \(3:5\). This means that for every 3 boys, there are 5 girls. If there are 240 girls, we can determine the number of boys by using the given ratio.
Let's set up the proportion based on the ratio:
\(\frac{\text{Boys}}{\text{Girls}} = \frac{3}{5}\)
We know there are 240 girls, so we can substitute into the proportion:
\(\frac{\text{Boys}}{240} = \frac{3}{5}\)
To find the number of boys, we cross-multiply:
\(\text{Boys} \times 5 = 3 \times 240\)
Simplifying the right side of the equation, we have:
\(\text{Boys} \times 5 = 720\)
Now, solve for the number of boys:
\(\text{Boys} = \frac{720}{5} = 144\)
Therefore, the number of boys in the school is 144.
The correct answer is 144.