Averages, simple arithmetic mean problems, answers : CAT MBA Entrance classes

Question 4 the day : June 12, 2003
The question for the day is a sample practice problem in Simple Average, Arithmetic Mean - an Arithmetic Topic and the problem provides an understanding of the different concepts related to Averages.

Question
The average age of a family of 5 members is 20 years. If the age of the youngest member be 10 years then what was the average age of the family at the time of the birth of the youngest member?

1. 13.5
2. 14
3. 15
4. 12.5

Correct Answer is 12.5. Correct Choice is (4)

Explanatory Answer

At present the total age of the family = 5 * 20 = 100

The total age of the family at the time of the birth of the youngest member = [100-10-(10*4)] = 50

Therefore, average age of the family at the time of birth of the youngest member = 50/4 = 12.5.

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