TANCET - XAT Quant Question : Simple Average

The question is from the topic average in arithmetic. It is a problem based on the concept of simple average.

Question

The average of 5 quantities is 6. The average of 3 of them is 8. What is the average of the remaining two numbers?

1. 6.5
2. 4
3. 3
4. 3.5
5. 4.2

Correct Answer - 3 . Choice (3).

Explanatory Answer

The average of 5 quantities is 6.
Therefore, the sum of the 5 quantities is 5 * 6 = 30.

The average of three of these 5 quantities is 8.
Therefore, the sum of these three quantities = 3 * 8 = 24

The sum of the remaining two quantities = 30 - 24 = 6.
Average of these two quantities = = 3.

Note

From the answer choices, you can eliminate choices (1) and (2) even without solving the question.

As the average of the 5 quantities is 6 and the average of three of these five is 8, the average of the remaining two should be a value that is less than 6. So choice (1) which is more than 6 can be eliminated.

If there were a total of four quantities and the overall average was 6 and the average of 2 of the four were 8, then the average of the remaining two would have been 4. i.e., the simple average of 4 and 8 is 6. However, we have unequal number of quantities. Hence, choice (2) can be eliminated.



Correct answer choice (4)

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