# Average (5)

1. A batsman makes a score of 87 runs in the 17th inning and thus increases his averages by 3. What is his average after 17th inning?
1. 39
2. 35
3. 42
4. 40.5

Explanation :-

Let the average after 17th innings = x
Therefore.  average after 16th innings = x − 3
Therefore,
16(− 387 17x16 (x−3) + 87 = 17x
39

2. A student needed to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found the mean to be 12. What is the value of x?
1. 12
2. 5
3. 7
4. 9

Explanation :-

(3 + 11 + 7 + 9 + 15 + 13 + 8 + 19 + 17 + 21 + 14 + x) / 12 = 12.
137 + x = 144
x = 144 – 137 = 7.

3. Arun obtained 76, 65, 82, 67 and 85 marks (out in 100) in English, Mathematics, Chemistry, Biology and Physics. What is his average mark?
1. 53
2. 54
3. 72
4. 75

Explanation :-

Average Marks = (76 65 82 67 85) / 5 = 375/5 = 75 Marks

4. 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 56km per hour. Find the average speed of the train during the whole journey?
1. 69.0 km /hr
2. 69.2 km /hr
3. 67.2 km /hr
4. 67.0 km /hr

Explanation :-

Average speed = [2xy / (x + y) ] km/hr.
x = 84 kmph.
y = 56 kmph.
Average speed, = [(2 * 84 * 56) / (84 + 56)] = 67.2 km/h.

5. The average age of boys in a class is 16 years and that of the girls is 15 years. What is the average age for the whole class?
1. 15
2. 16
3. 15.5
4. Insufficient Data