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 of 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:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e 11.
| Understanding/Application |
|
Let the total number of people be x. Wrong average of people = 35 Total age of wrong average people = 35x |
|
Correct average = 35 - 2.5 = 32.5 Total age for correct average = 32.5x Correct age of 2 persons = 29 + 22 = 51 Wrong age of 2 persons = 38.5 + 40 = 78.5 Difference = 78.5 - 51 35x - 32.5x = 27.5 x = 27.5/2.5 x = 11 |