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?

Question

parthkohli · Answer

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

parthkohli · Answer

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

parthkohli · Answer

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

parthkohli · Answer

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

anonymous · Answer

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