Question

A group of boys has an average weight of 44 kg. One boy weighing 50 kg leaves the group and another boy weighing 40 kg joins the group. If now the average weight of group is 42 kg, then how many boys are there in the group?
1. 5
2. 4
3. 7
4. 9

Answer 1

Correct Answer - Option 1 : 5

Given:

The average weight of the group = 44 kg

Formula used:

\(Average\ =\ {The\ sum\ of\ the\ all\ items \over The\ total\ number\ of\ items}\)

Calculation:

Let us assume the total boys in the group be X

⇒ The sum of the weight of the all-boys = 44X

⇒ 42X = 44X - 50 + 40

⇒ 42X = 44X - 10

⇒ 44X - 42X = 10

⇒ 2X = 10

⇒ X = 5

∴ The required result will be 5.