Averages Quiz Set 016

The sums of the weights of all the students is 20 × 2 + 40 × 5 + 30 × 2 = 300. The required average = 300/total students = $300/{20 + 40 + 30}$ = ${10/3}$, which is same as: $3{1/3}$.

Let the present ages of the three friends be a, b and c. We are given ${(b - 5) + (c - 5)}/2$ = 19. Which gives b + c = 48. We are also given ${(a - 3) + (b - 3) + (c - 3)}/3$ = 33, which gives a + b + c = 3 * 33 + 9 = 108. Putting b + c here we get a = 108 - (b + c) = 108 - 48 = 60 years.

Let the present ages of the three friends be a, b and c. We are given ${(b - 5) + (c - 5)}/2$ = 12. Which gives b + c = 34. We are also given ${(a - 3) + (b - 3) + (c - 3)}/3$ = 31, which gives a + b + c = 3 * 31 + 9 = 102. Putting b + c here we get a = 102 - (b + c) = 102 - 34 = 68 years.

The total sale on first six days is 3594 + 4422 + 1800 + 2724 + 732 + 4164 = 17436. The average for 6 days is: 17436/6, which gives Rs. 2906.

Total weight of 19 students is 19 × 39 = 741. Similarly, the total weight of remaining 12 students is 12 × 38 = 456. The total weight of all 31 students is 741 + 456 = 1197. So the average = 1197/31 = $38{19/31}$.