Question

5 children are playing on a trampoline.

The mean weight of the 5 children is 28 kg.
2 of the children get off the trampoline.
The mean weight of these 2 children is 26.5 kg.
Work out the mean weight of the 3 children who remain on the trampoline.

Answer 1

29

Explanation:

The mean weight is the average

(x1+x2+x3+x4+x5)/5 = 28

Multiply by 5

(x1+x2+x3+x4+x5) =140

The total weight of the 5 children is 140

(x1+x2)/2 =26.5

Multiply by 2

(x1+x2)/2*2 =26.5*2

(x1+x2) =53

The total weight of the two children is 53

140-53 =87

The three children weigh 87

Divide by 3 to find the mean weight

(x3+x4+x5)/3 = 87/3

mean weight = 29