Average (4)

1. 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, what is the weight of B?
1. 31 kg
2. 2812 kg
3. 32 kg
4. 3012 kg

Answer & Explanation

Answer:- 1

Explanation :-

Total weight of A, B & C = 45 x 3 = 135
Total Weight of A & B = 40 x 2 = 80 ———(1)
Total Weight of B & C = 43 x 2 = 86 ———(2)
Adding (1) & (2)
A + B + B + C = 80 + 86 = 166
But we know , Total weight of A, B & C (A+ B + C) = 45 x 3 = 135
Therefore 135 + B = 166
B = 166 – 135 = 31 kg
B’s weight = 31 kg.

 

2. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, what is the average marks of all the students?
1. 53.23
2. 54.68
3. 51.33
4. 50

Answer & Explanation

Answer:- 2

Explanation :-

Average marks of All students = [(55*50) + (60*55) + (45*60)] / (55 + 60 + 45)
= (2750 + 3300 + 2700) / (160)
= (8750/160) = 54.68

 

3. The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. What is the present age of the husband?
1. 40
2. 32
3. 28
4. 30

Answer & Explanation

Answer:- 1

Explanation :-

Sum of the present ages of husband, wife and child = (27 * 3 + 3 * 3) years = 90 years.
Sum of the present ages of wife and child = (20 * 2 + 5 * 2) years = 50 years.
Husband’s present age = (90 – 50) years = 40 years

 

4. The average weight of 8 person’s increases by 2.5 kg when a new person comes in place of one of them weighing
65 kg. What is the weight of the new person?
1. 75 Kg
2. 50 Kg
3. 85 Kg
4. 80 Kg

Answer & Explanation

Answer:- 3

Explanation :-

Total weight increased = 2.5 * 8 = 20.
weight of new person = 65 + 20 = 85

 

5. There are two divisions A and B of a class, consisting of 36 and 44 students respectively. If the average weight of divisions A is 40 kg and that of division b is 35 kg. What is the average weight of the whole class?
1. 38.25
2. 37.25
3. 38.5
4. 37

Answer & Explanation

Answer:- 2

Explanation :-

Average weight of Whole Class = [(36*40) + (44*35)] / (36 + 44) = (1440 + 1540)/ 80 = 37.25 kg

 

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