Discussion of Question with ID = 058 under Averages

This is the discussion forum for this question. If you find any mistakes in the solution, or if you have a better solution, then this is the right place to discuss. A healthy discussion helps all of us, so you are requested to be polite and soft, even if you disagree with the views of others. The question and its current solution has also been given on this page.

Advertisement

Question

Average weight of a group of 8 boys is 89 Kg. Later it was found that the weighing machine was showing 4 Kg more than the actual weight. What is the actual average weight?

A

85.

B

86.

C

84.

D

83.

Soln.
Ans: a

Let the total weight of the group as measured with the faulty machine be x. Then, by average formula $89 = x/8$, which gives x = $89 × 8 = 712$. When weight of each of the 8 boys is reduced by 4 Kg, the new total becomes $712 - 8 × 4 = 680$, the new average becomes $680/8 = 85$. TIP: As a shortcut, the new average = old average - error in weighing machine.


Comments and Discussion