Average

Question:
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. The present age of the husband is:

[A].

35 years

[B].

40 years

[C].

50 years

[D].

None of these

Answer: Option B

Explanation:

Sum of the present ages of husband, wife and child = (27 x 3 + 3 x 3) years = 90 years.

Sum of the present ages of wife and child = (20 x 2 + 5 x 2) years = 50 years.

Husband’s present age = (90 – 50) years = 40 years.

Question: 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 might be the weight of the new person?
[A].

76 kg

[B].

76.5 kg

[C].

85 kg

[D].

Data inadequate

Answer: Option C

Explanation:

Total weight increased = (8 x 2.5) kg = 20 kg.

Weight of new person = (65 + 20) kg = 85 kg.

Video Explanation: https://youtu.be/ceg2jvHsiJU

Question:
The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. What is the average age of the team?

[A].

23 years

[B].

24 years

[C].

25 years

[D].

None of these

Answer: Option A

Explanation:

Let the average age of the whole team by x years.

11x – (26 + 29) = 9(x -1)

11x – 9x = 46

2x = 46

x = 23.

So, average age of the team is 23 years.

Question:
The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:

[A].

3500

[B].

4000

[C].

4050

[D].

5000

Answer: Option B

Explanation:

Let P, Q and R represent their respective monthly incomes. Then, we have:

P + Q = (5050 x 2) = 10100 …. (i)

Q + R = (6250 x 2) = 12500 …. (ii)

P + R = (5200 x 2) = 10400 …. (iii)

Adding (i), (ii) and (iii), we get:  2(P + Q + R) = 33000  or   P + Q + R = 16500 …. (iv)

Subtracting (ii) from (iv), we get P = 4000.

P’s monthly income = Rs. 4000.

Question:
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

Answer: Option D

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.

Question: 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

Answer: Option C

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

Question: In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the run rate in the remaining 40 overs to reach the target of 282 runs?
[A].

6.25

[B].

6.5

[C].

6.75

[D].

7

Answer: Option A

Explanation:

Required run rate =		282 – (3.2 x 10)		=	250	= 6.25
		40			40

Video Explanation: https://youtu.be/GhK9d8tcqvA

Question: A grocer has a sale of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs. 6500?
[A].

Rs. 4991

[B].

Rs. 5991

[C].

Rs. 6001

[D].

Rs. 6991

Answer: Option A

Explanation:

Total sale for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.

Required sale = Rs. [ (6500 x 6) – 34009 ]

   = Rs. (39000 – 34009)

   = Rs. 4991.

Video Explanation: https://youtu.be/tP4hszReksU

Question: A car owner buys petrol at Rs.7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year?
[A].

Rs. 7.98

[B].

Rs. 8

[C].

Rs. 8.50

[D].

Rs. 9

Answer: Option A

Explanation:

Total quantity of petrol consumed in 3 years	= 4000 + 4000 + 4000  litres 7.50 8 8.50
	= 4000 2 + 1 + 2  litres 15 8 17
	= 76700  litres 51

Total amount spent = Rs. (3 x 4000) = Rs. 12000.

Average cost = Rs.		12000 x 51		= Rs.	6120	= Rs. 7.98
		76700			767

Question:
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

Answer: Option C

Explanation:

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