Average important questions with short tricks | Online bank exam test series for SBI PO Pre

1

There are 7 friends. If salaries of these friends are in order-
10K = S1 ≥ S2 ≥ S3 ≥ S4 ≥….. ≥ S7 = 5K

Which of the following can’t be the average of these 7 friends.

» Explain it

Correct Option: C

Maximum average could be

=	(10 + 10 + 10 + 10 + 10 + 10 + 5)	= 9.28
	7

Which is being satisfied by option C i.e. 9.42.

Hence, option (C) is correct.

1

7 मित्र हैं। यदि इन मित्रों का वेतन क्रम में हो-

10K = S1 ≥ S2 ≥ S3 ≥ S4 ≥… .. S7 = 5K

निम्नलिखित में से कौन इन 7 मित्रों का औसत नहीं हो सकता है।

» Explain it

सही विकल्प : C

Maximum average could be

=	(10 + 10 + 10 + 10 + 10 + 10 + 5)	= 9.28
	7

Which is being satisfied by option C i.e. 9.42.

Hence, option (C) is correct.

2

The average age of A and B is 20 years. If A is to be replaced by C, the average would be 19 years. The average age of C and A is 21 years. The ages of A, B and C in order (in years) are

» Explain it

Correct Option: C

A + B = 2 × 20 = 40 yr

B + C = 2 × 19 = 38 yr

C + A = 2 × 21 = 42 yr

On adding all three,

2 (A + B + C) = 40 + 38 + 42 = 120

⇒ A + B + C = 60

∴ A = (A + B + C) – (B + C) = 60 – 38 = 22 yr

Similarly,

B = (A + B) – A = 40 – 22 = 18 yr

C = (C + A) – A = 42 – 22 = 20 yr

Note: In this question we can save 4-5 seconds by not calculating the age of the third person as with only the respective ages of A and B we can confirm the correct answer out of the given options.

Hence, option (C) is correct.

2

A तथा B की औसत आयु 20 वर्ष है। यदि A को C से बदला जाए, तो औसत 19 वर्ष होगा। C तथा A की औसत आयु 21 वर्ष है। A, B और C की आयु क्रम में (वर्षों में) कितनी होगी?

» Explain it

सही विकल्प : C

A + B = 2 × 20 = 40 yr

B + C = 2 × 19 = 38 yr

C + A = 2 × 21 = 42 yr

On adding all three,

2 (A + B + C) = 40 + 38 + 42 = 120

⇒ A + B + C = 60

∴ A = (A + B + C) – (B + C) = 60 – 38 = 22 yr

Similarly,

B = (A + B) – A = 40 – 22 = 18 yr

C = (C + A) – A = 42 – 22 = 20 yr

Note: In this question we can save 4-5 seconds by not calculating the age of the third person as with only the respective ages of A and B we can confirm the correct answer out of the given options.

Hence, option (C) is correct.

3

The average monthly income of a family of four earning members was Rs. 15130. One of the daughters in the family got married and left home, so the average monthly income of the family came down to Rs. 14660. What is the monthly income of the married daughter ?

» Explain it

Correct Option: C

Total monthly income of 4 members = 15130 × 4 = Rs. 60520

Except daughter, total monthly income of 3 members = 14660 × 3 = Rs. 43980

∴ Monthly income of married daughter = 60520 – 43980 = Rs. 16540

Hence, option (C) is correct.

3

चार कमाने वाले सदस्यों के एक परिवार की औसत मासिक आय 15130 रुपये थी। परिवार की एक बेटी की शादी हो गई और उसने घर छोड़ दिया, जिससे परिवार की औसत मासिक आय घटकर 14660 रुपये रह गई। विवाहित पुत्री की मासिक आय कितनी है ?

» Explain it

सही विकल्प : C

Total monthly income of 4 members = 15130 × 4 = Rs. 60520

Except daughter, total monthly income of 3 members = 14660 × 3 = Rs. 43980

∴ Monthly income of married daughter = 60520 – 43980 = Rs. 16540

Hence, option (C) is correct.

4

A man purchases milk for three consecutive years. In the first year, he purchases milk at the rate of Rs. 7.50 per litre, in the second year, at the rate of Rs. 8.00 per litre and in the third year, at Rs. 8.50 per litre. If he purchases milk worth Rs. 4,080 each year, the average price of milk per litre for the three years is

» Explain it

Correct Option: B

Price of milk in first year = Rs. 7.50 per litre.

∴ Quantity of milk in first year =	4080	= 544 litres
	7.50

Price of milk in second year = Rs. 8.00 per litre.

∴ Quantity of milk in second year =	4080	= 510 litres
	8.00

Price of milk in third year = Rs. 8.50 per litre.

∴ Quantity of milk in third year =	4080	= 480 litres
	8.50

∴ Required average =	3 × 4080
	544 + 510 + 480

=	12240	= Rs. 7.98
	1534

Hence, option (B) is correct.

4

एक व्यक्ति लगातार तीन वर्षों तक दूध खरीदता है। पहले वर्ष में वह 7.50 रुपये प्रति लीटर की दर से, दूसरे वर्ष में 8.00 रुपये प्रति लीटर की दर से और तीसरे वर्ष में 8.50 रुपये प्रति लीटर की दर से दूध खरीदता है। यदि वह प्रत्येक वर्ष 4,080 रुपये का दूध खरीदता है, तो तीन वर्षों के लिए प्रति लीटर दूध का औसत मूल्य कितना होगा?

» Explain it

सही विकल्प : B

Price of milk in first year = Rs. 7.50 per litre.

∴ Quantity of milk in first year =	4080	= 544 litres
	7.50

Price of milk in second year = Rs. 8.00 per litre.

∴ Quantity of milk in second year =	4080	= 510 litres
	8.00

Price of milk in third year = Rs. 8.50 per litre.

∴ Quantity of milk in third year =	4080	= 480 litres
	8.50

∴ Required average =	3 × 4080
	544 + 510 + 480

=	12240	= Rs. 7.98
	1534

Hence, option (B) is correct.

5

The average weight of 21 boys was recorded as 64 kg. If the weight of the teacher was added, the average increased by one kg. What was the teacher's weight ?

» Explain it

Correct Option: A

Total weight of 21 boys = 64 × 21 = 1344 kg

Given that if the weight of the teacher was added, the average increased by one kg

∴ Total weight along with the teacher = 65 × 22 = 1430 kg

Now, teacher's weight = 1430 – 1344 = 86

Hence, option (A) is correct.

5

21लड़कों का औसत वजन 64 किलो दर्ज किया गया। यदि शिक्षक के भार को जोड़ दिया जाए, तो औसत में एक किग्रा की वृद्धि होती है। शिक्षक का वजन कितना था?

» Explain it

सही विकल्प : A

Total weight of 21 boys = 64 × 21 = 1344 kg

Given that if the weight of the teacher was added, the average increased by one kg

∴ Total weight along with the teacher = 65 × 22 = 1430 kg

Now, teacher's weight = 1430 – 1344 = 86

Hence, option (A) is correct.

Loading...

Join Testzone, Smartkeeda’s Test Series Platform for:

Download the all new Smartkeeda App for better experience.

Bank Exams Test Series

Other Exam Test Series

Insurance Test Series

State Exams Test Series

SSC Exams Test Series

Railways Test Series

Teaching Test Series

UPSSSC

Common Eligibility Test (NRA)

LAW Test Series

Loading...

Join Testzone, Smartkeeda’s Test Series Platform for:

Download the all new Smartkeeda App for better experience.