The average age of a number of persons in a group was calculated as 35 years, which was 2.5 years more than the correct average as there was an error in recording the age to two persons as 38.5 years and 40 years instead of 29 years and 22 years respectively. The number of persons in the group was:?

15
12
11
13

LohaHridoy

7 views

2025-01-04 04:42

1 Answers

AhmedNazir

Option 3 : 11

Let the number of persons in the group be x, then

Wrong average of age of persons in the group = 35

Wrong sum of age of person in the group = 35x

Correct average of age of persons in the group = 35 – 2.5 = 32.5

Correct sum of age of persons in the group = 32.5x

According to the question

35x – 32.5x = 38.5 + 40 – 29 – 22

⇒ 2.5x = 27.5

⇒ x = 27.5/2.5

⇒ x = 11

Short Trick:

Total number of persons in the group = (38.5 + 40 – 29 – 22)/2.5 = 11

7 views Answered 2022-09-04 04:29

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