Question

The mean mass of 5 boys is 62 kg. When the mass of a boy is excluded, the mean mass of the remaining 4 boys becomes 64 kg. Find the mass of the boy that has been excluded

Answer 1

54 kg

Explanation:

x - regular boy

y - special boy who's weight we're counting

The mean mass of 5 boys:

(4x+y)÷5=62

The mean mass of 4 boys:

4x÷4=64

x=64kg

the mass of y boy:

(4×64+y)÷5=62

(256+y)÷5=62 |×5

256+y=310

y=310-256

y=54