Average

Question:
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

Answer: Option D

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

Question: A family consists of two grandparents, two parents and three grandchildren. The average age of the grandparents is 67 years, that of the parents is 35 years and that of the grandchildren is 6 years. What is the average age of the family?
[A].

28	4	years
	7

[B].

31	5	years
	7

[C].

32	1	years
	7

[D].

None of these

Answer: Option B

Explanation:

Required average	= 67 x 2 + 35 x 2 + 6 x 3 2 + 2 + 3
	= 134 + 70 + 18 7
	= 222 7
	= 31  5 years. 7

Video Explanation: https://youtu.be/OXLnoItd0MA

Question: In Arun’s opinion, his weight is greater than 65 kg but less than 72 kg. His brother doest not agree with Arun and he thinks that Arun’s weight is greater than 60 kg but less than 70 kg. His mother’s view is that his weight cannot be greater than 68 kg. If all are them are correct in their estimation, what is the average of different probable weights of Arun?
[A].

67 kg.

[B].

68 kg.

[C].

69 kg.

[D].

Data inadequate

Answer: Option A

Explanation:

Let Arun’s weight by X kg.

According to Arun, 65 < X < 72

According to Arun’s brother, 60 < X < 70.

According to Arun’s mother, X <= 68

The values satisfying all the above conditions are 66, 67 and 68.

Required average =		66 + 67 + 68		=		201		= 67 kg.
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