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The average weight of a group of 20 boys was calculated to be 65 kg and it was later discovered that the weight of a boy was misread as 76 kg instead
Question

The average weight of a group of 20 boys was calculated to be 65 kg and it was later discovered that the weight of a boy was misread as 76 kg instead of the correct weight 66 kg. The correct average weight was:

A.

65.5 kg

B.

64.5 kg

C.

66 kg

D.

63 kg

Correct option is B

Given:

Number of boys = 20

Incorrect weight = 76 kg

Correct weight = 66 kg

Initial average weight = 65 kg

Formula Used:

Total weight =Average× \times​ Number of boys

Solution:

Total weight =Average  × \times ​Number of boys

Total weight = 65× \times​ 20 = 1300

Correcting the total weight = Total weight - Incorrect weight + Correct weight

Correcting the total weight = 1300 - 76 + 66 = 1290

Correct Average = Total correct weight/Number of boys

Correct Average = 129020\frac{1290}{20}​ = 64.5 kg

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