The ones who are crazy enough to think they can change the world are the ones who do.

- Steve Jobs

Problems on Average

Average - Aptitude

6. The average weight of 10 oarsmen in a boat is increased by 1.5 kg when one of the crew, who weighs 50 kg is replaced by a new man.Find the weight of the new man.

x

Option: C

Explanation

Total weight increased = (1.5 * 10)kg = 15 kg

Weight of new man = (50 + 15)kg = 65 kg

✉ Answer

7. A batsman makes a score of 77 runs in the 15th inning and thus increases his average by 3.Find his average after 15th inning.

x

Option: B

Explanation

Let the average after 15th inning = X

then, the average after 14th inning = (X - 3)

i.e) 14(X - 3) + 77 = 15X

14X + 35 = 15X

Batsman's average afer 15th inning X = 35

✉ Answer

8. Five persons went to a hotel for taking their meals. Four of them spent Rs.10 each on their meals and the fifth spent Rs.8 more than the average expenditure of all the five. What was the total money spent by them.

x

Option: B

Explanation

Let the average expenditure of all the five be Rs.x

Then, (10 * 4) + (x + 4) = 5x

40 + x + 4 = 5x

4x = 44

x = 11

Total money spent = 5x = (5 * 11) = Rs.55

✉ Answer

9. There were 35 students in a hostel. Due to the admission of 7 new students, the expenses of the mess were increased by Rs.42 per day while the average expenditure per head diminished by Re.1. What was the original expenditure of the mess?

x

Option: B

Explanation

Let the original average expenditure be Rs.x

Then, 42(x - 1) - 35x = 42

7x = 84

x = 12

Original expenditure = Rs.(35 * 12) = Rs.420

✉ Answer

10. Distance between two stations A and B is 778 km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56 km per hour. Find the average speed of the train during the whole journey.