AVERAGE AND AGES (QUANTITATIVE APTITUDE) EPFO UPSC

Total Questions: 30

11. The mean of 50 numbers is 30. Later it was discovered that two entries were wrongly entered as 82 and 13 instead of 28 and 31. Find the correct mean.

Correct Answer: (c) 29.28
Solution:

12. If the average of 39, 48, 51, 63, 75, 83, x and 69 is 60, then the value of x is

Correct Answer: (a) 52
Solution:

13. The mean of 19 observation is 24. If the mean of the first 10 observations is 17 and that of the last 10 observations is 24, find the 10th observation.

Correct Answer: (c) – 46
Solution:

14. The average of four consecutive even numbers is 9. Find the largest number.

Correct Answer: (a) 12
Solution:

15. Out of 10 teachers of a school, one teacher retires and in his place, a new teacher of age 25 years joins. As a result, average age of teachers is reduced by 3 years. The age (in years) of the retired teacher is :

Correct Answer: (d) 55
Solution:Age of retired teacher = 25 + 3 × 10 = 55 years

16. The average of 50 numbers is 38. If two numbers namely 45 and 55 are discarded, the average of the remaining numbers is :

Correct Answer: (d) 37.5
Solution:

17. The average of 20 numbers is 15 and the average of first five is 12. The average of the rest is

Correct Answer: (a) 16
Solution:

18. Out of 20 boys, 6 are each of 1 m 15 cm height, 8 are of 1 m 10 cm and rest of 1 m 12 cm. The average height of all of them is

Correct Answer: (b) 1 m 12.1 cm
Solution:

19. The average of 30 numbers is 40 and that of other 40 numbers is 30. The average of all the numbers is

Correct Answer: (b) 34²⁄₇
Solution:

20. The average weight of 15 oarsmen in a boat is increased by 1.6 kg when one of the crew, who weighs 42 kg is replaced by a new man. Find the weight of the new man (in kg).

Correct Answer: (b) 66
Solution: