If 10% of a number equals 30, find 40% of that number.

120

Step-by-step explanation:

So 10% of a number (let's use n) is 30.

The key word "of" tells us we need to multiply. Therefore, 10% times n is 30:

10% is the same as 0.1. So:

Divide both sides by 0.1:

So, our number is 300.

To find 40% of 300, multiply 0.4 and 300. Thus:

Our answer is 120.

And we're done!

36 girls

step-by-step explanation:

the 48 boys is 4 parts of the ratio

divide 48 by 4 to obtain one part of the ratio

= 12 ← 1 part of the ratio

3 parts = 3 × 12 = 36 ← number of girls