Arithmatic Mean Question Answers

Averages Practice Questions : CAT 2007 Quant Preparation

Question 4 the day : June 26, 2003
The question for the day is from the topic Averages. It is a question on simple average.

Question
The average of 5 quantities is 10 and the average of 3 of them is 9. What is the average of the remaining 2?

1. 11
2. 12
3. 11.5
4. 12.5

Correct Answer is 11.5. Choice (3) is right.

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Explanatory Answer

The average of 5 quantities is 10.
Therefore, the sum of all 5 quantities is 50.

The average of 3 of them is 9.
Therefore, the sum of the 3 quantities is 27.

Therefore, the sum of the remaining two quantities = 50 - 27 = 23.
Hence, the average of the 2 quantities = 23/2 = 11.5.