Averages Problems with Answers page 2

quantitative aptitude

6) Average of 13 results is 65. If the average of first six results is 61 and average of last six results is 59 Then find the seventh result?

Answer: 125

7) The average weight of a class of 20 boys was calculated to be 58.4 kgs and it was later found that one weight was misread as 56 kg instead of 65 kg. What is the correct weight?

Answer: 58.85kg


Actual total weight is (20X 58.4 – 56 + 65) = 1177 Kgs

Actual average weight is 1177/20 = 58.85kgs

8) The average of 10 numbers is 25. The average of first three numbers is 22 1/3 and that of next five is 15 1/5. If the eighth be less than the ninth and tenth numbers by 5 and 11 respectively, then the tenth number is:

Answer: 41

9) The average age of father and his two sons is 27 Years. Five years ago, the average age of the two sons was 12 Years. If the difference between the ages of the two sons is four years, what is the present age of the father?

Answer: 47


The total present age of father and two sons is 3S27 = 81 yrs

The total present age of sons is (12+5) X 2 = 34Years

so, present age of father is 81 – 34 = 47 yrs

10) There were 45 students in a hostel, if the numbers of students increased by 7, the expenses of the mess were increased by Rs. 39 per day while the average expenditure per head diminished by Re.1. What is the original expenditure of the mess?

Answer: Rs. 585


Let the original expenditure be Rs.x

Original average expenditure = X/45

New average expenditure = (x+39)/52

So (x/45) – ((x+39) / 52) = 1  so x = 585

so, original expenditure is Rs 585