Aptitude - Averages Online Quiz


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Following quiz provides Multiple Choice Questions (MCQs) related to Averages. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Questions and Answers

Q 1 - If in a class room r boys is the average age in a year. What should be the average of remaining boys if b is the average age of s boys out of them?

A - (ra-sb)/(r-s)

B - (ra-sb)/(s-b)

C - (sa-sb)/(b-s)

D - (ra-sb)/(r+s)

Answer : A

Explanation

r boys have the sum of the age = (ra ) years.
s  boys have the sum of the age = (sb) years.
(r-s) boys have the sum of the ages = (ra-sb)
(r-s) boys have the average of the ages = (ra-sb)/ (r-s).

Q 2 - 44 is the average of 100 numbers. If we add 4 new numbers in 100 numbers then average will be 50 then what should be the average value of new 4 numbers?

A - 100

B - 200

C - 400

D - 500

Answer : B

Explanation

The value of 100 number=  (44*100) = 4400
The value of 104 number = ( 50*104)=   5200
∴ value of 4 new number = 5200- 4400 = 800
Then the  average value of the 4 numbers = 800/4 = 200

Q 3 - A committee have 8 person. If 35 year and 45 year aged lady replaced by two men in that case the average of age become more 2 year in the comparison of old one. Find out the average age of two men?

A - 24

B - 35

C - 54

D - 48

Answer : D

Explanation

Age increase  = (2*8) = 16 years.
Total age of two lady  who replaced = (35+45)= 80
Total age of two man  = (80+16) =96
Average age of those men = 96/2 = 48.
Hence, is 48 the required  average age.

Q 4 - 84 kg is the average weight of 3 people A, B and C. 80 kg is the average if D joins the group. A new man E replaces who have 3kg more weight than D. At that time 79 kg is the average weight of B, C, D and E. What should be the weight of A?

A - 75 kg

B - 34 kg

C - 26 kg

D - 56 kg

Answer : A

Explanation

A+B+C= (3*84)= 252 kg.     A+B+C+D= (4*80)= 320 kg
weight of D =( 320- 252) =68 kg.   weight of E = (68+3)= 71 kg.
sum of the weight of B+C+D+E= (79*4)= 316 kg ,
sum of the weight of B+C+D = (316-71)=245kg.
Total weight of A = (320- 245 )= 75 kg.

Q 5 - 40 year is the average of the class. 32 years is the average of the class if 12 new students also add in this class. Find out the number of students in the class?

A - 15

B - 16

C - 17

D - 12

Answer : D

Explanation

x is the strength of the class.
40x+12*32 = 36* (x+12) ⇒ 4x =(432- 384) = 48 ⇒ x = 12
∴ original strength = 12

Q 6 - 450 is the sum of four numbers and 50 is the mean. Find out the new mean if 100 more numbers included?

A - 15

B - 67

C - 55

D - 45

Answer : C

Explanation

If the number  of numbers be A. then,
50A= 450 ⇒ A = 9

Q 7 - The average of runs of a cricket player of 10 innings was 32. How many runs must he make in his next innings so as to increase his average of runs by 4?

A - 2

B - 70

C - 4

D - 76

Answer - D

Explanation

Average after 11 innings = 36. 
Therefore Required number of runs = (36 x 11) - (32 x 10) = 396 - 320 = 76.

Q 8 - Of the three numbers, the average of the first and the second is greater than the average of the second and the third by 15. What is the difference between the first and the third of the three numbers?

A - none

B - 15

C - 45

D - 60

Answer - A

Explanation

Let the numbers be a, b, and c. 
Then, (a + b)2 - (b + c)2 = 15 or 
or (a + b) - (b + c) = 30 or a - c = 30 

Q 9 - 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 - 25

B - none

C - 24

D - 23

Answer - B

Explanation

Let the average age of the whole team be z years. 
Therefore 11z - (26 + 29) = 9 (z - 1) = 11z - 9z = 46 
= 2z = 46
= z = 23 

So, average age of team is 23 years.

Q 10 - In an examination, a pupil's average marks were 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his history paper, his average per paper would have been 65. How many papers were there in the examination?

A - 9

B - 10

C - 11

D - 8

Answer - C

Explanation

Let the number of papers be z. Then, 63z + 20 + 2 = 65z 

2z = 22 or z = 11

aptitude_averages.htm

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