Averages, weighted average, simple arithmetic mean problems : Ascent - CAT Coaching Institute

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.

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.

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