Question

Average weight of 20 students in a class is 45.if two students of weight X and X+4 kg joined the class.then average weight increased by 1. Find the average weight of two new students

Answer 1

Step-by-step explanation:

Given average weight of whole class decreases by 1 kg, thus on a whole since there are 20 students , the net weight decrement is 20*1 = 20 and since a new student weight is 40kgs , therefore replaced student weight should be 40 + 20 = 60kgs.

Aliter:

Let weights of the students are w₁, w₂,......,w₂₀ and let w₂₀ be the weight of the student whose weight is replaced.

A₁ = (w₁+w₂+.....w₁₉+w₂₀)/20 =45

A₂ = (w₁+w₂+.....w₁₉+40)/20 = 44

A₁-A₂ gives (w₂₀-40)/20 = 1,

Thus w₂₀ = 60.