Question

The mean mass of 8 boys is 55 kg and the mean mass of a group of girls is 52 kg.The mean mass of all the children is 53.2 kg. How many girls are there?

Answer 1

The total weight of boys is \(\rm 55 \times 8 = 440\).

Answer 2

Let's introduce a variable \(\rm \large n\) standing for number of girls.

Answer 3

Your equation is:\[\large \rm {440 +52n \over n + 8} =53.2 \]

Answer 4

Can you solve that equation? Please ask if you don't know how I got the above.

Answer 5

How did you get this equation total weight / number of children?