Averages, change in average, simple arithmetic mean problems tests, Answers : Ascent - CAT MBA Entrance classes

Question 4 the day : October 21, 2003
The question for the day is a sample practice problem in Simple Average, Arithmetic Mean on change in the average with change in number of elements - an Arithmetic Topic and the problem provides an understanding of the different concepts related to Averages.

Question
The average age of a group of 12 students is 20 years. If 4 more students join the group, the average age increases by 1 year. The average age of the new students is

1. 24
2. 26
3. 26
4. 22

Correct Answer is 24 years. Correct Choice is (1)

Explanatory Answer

Total age of 12 students = 12 * 20 = 240 and the total age of 16 students = 21*16 = 336.

Let the average age of 4 new students be x.

Therefore total age of the new students = 4x.

Hence the total age of 16 students = 240 + 4x = 336 => x = 24.

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