# Aptitude - Average

### Exercise :: Average - General Questions

11.

The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is:

 A. 17 kg B. 20 kg C. 26 kg D. 31 kg

Explanation:

Let A, B, C represent their respective weights. Then, we have:

A + B + C = (45 x 3) = 135 .... (i)

A + B = (40 x 2) = 80 .... (ii)

B + C = (43 x 2) = 86 ....(iii)

Adding (ii) and (iii), we get: A + 2B + C = 166 .... (iv)

Subtracting (i) from (iv), we get : B = 31. B's weight = 31 kg.

12.

The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg. Find the average weights of all the boys in the class.

 A. 47.55 kg B. 48 kg C. 48.55 kg D. 49.25 kg

Explanation:

Required average
 = 50.25 x 16 + 45.15 x 8 16 + 8
 = 804 + 361.20 24
 = 1165.20 24
= 48.55

13.

A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is:

 A. 250 B. 276 C. 280 D. 285

Explanation:

Since the month begins with a Sunday, to there will be five Sundays in the month.

Required average
 = 510 x 5 + 240 x 25 30
 = 8550 30
= 285

14.

If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is:

 A. 53.33 B. 54.68 C. 55 D. None of these

Explanation:

Required average
 = 55 x 50 + 60 x 55 + 45 x 60 55 + 60 + 45
 = 2750 + 3300 + 2700 160
 = 8750 160
= 54.68

15.

A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half (1/2). The number of pupils in the class is:

 A. 10 B. 20 C. 40 D. 73

Explanation:

Let there be x pupils in the class.

 Total increase in marks = x x 1 = x 2 2 x = (83 - 63) x = 20 x= 40. 2 2