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 - N2 is the average of m numbers and that of n number is m2, find the average of (m+n) numbers is ?

A - m-n

B - m+n

C - m/n

D - mn

Answer : D

Explanation

Total of (m+n)  numbers = (mn2+nm2)= mn(m+n)
Average of numbers( m+n) = mn(m+n)/ (m+n) = mn

Q 2 - 28 is the average of 3 numbers. Find out the value of third number if the given condition is such that the second number have the double value in the comparison of first number and third number have 4 times value of first number?

A - 48

B - 34

C - 22

D - 21

Answer : A

Explanation

If x is the value of third number.
Then  the value of second number is x/2 , if x/2 is the value of second number then the value of first number will be 1/2 . x/2 = x/4.
Total sum of three number = (3*28) =84
∴ x+x/2+x/4 = 84 ⇒ 7x/4 = 84 ⇒ x= (84*4)/7 = 48
So, its proves that the value of the third number is 48.

Q 3 - A class has 24 students. If 18 year old boys left the school and one new boy join the school in that situation the average decrease by 1 month. Find out the age of new boy?

A - 16 years

B - 17 years

C - 25 years

D - 23 years

Answer : A

Explanation

Downfall in the total age =( 24*1 )= 24 months =2 years
The age of the new boy = 18- 2 = 16 years.

Q 4 - The students who leave the school find out the average of their marks if 50 is the average of their marks if 50 is the average of 28 students. Condition is given that 55 is the average marks of 20 students.

A - 37.5

B - 24

C - 45

D - 36

Answer : A

Explanation

28 students have total marks = ( 28*50)= 1400
20 students have total marks = (55* 20) =1100
Total  of 8 those students who leaves the school = 1400- 1100 = 300
Required average = 300/8 = 37.5

Q 5 - What should be the average of monthly consumption if 110 ltr is the average of 7 month and Rs. 86 is the average for the next 5 month consumption?

A - 26 ltr

B - 34 ltr

C - 70 ltr

D - 100 ltr

Answer : D

Explanation

12 month consumptions = [(110*7)+(86*5)] ltr. = 1200 ltr.
∴ per month consumption = 1200/12 = 100 ltr.

Q 6 - Rs. 450 is average of 5 shirts and Rs.750 is the average of 4 trousers and 12 pair of shoes average is also Rs.750. Find out the average expenditure per product?

A - Rs 678.21

B - Rs 250

C - Rs 240

D - Rs 230

Answer : A

Explanation

sum of the all items = (450*5 +750*4+750*12) = Rs. 14250
Average expenditure  per product = Rs. 14250/21 = Rs. 678.21

Q 7 - The average price of 10 books is Rs. 12 while the average price of 8 of these books is Rs. 11.75. Of the remaining two books, if the price of one book is 60% and more than the price of the other, what is the price of each of these two books?

A - Rs. 5, Rs. 7.5

B - Rs. 8, Rs. 12

C - Rs. 10, Rs. 16

D - Rs. 12, Rs. 14

Answer - C

Explanation

Total price of the two books = Rs. [(12 x 10) - (11.75 x 8)] = Rs. (120 - 94) = Rs. 26. 
Let the price of one book be Rs. z. 
Then, the price of other book = Rs. (z + 60% of z) = Rs. ( z + 3z5) = Rs. 8z5 
So, z + 8z5 = 26 = 13z = 130 = z = 10. 
Therefore The price of the two books are Rs. 10 and Rs. 16.

Q 8 - 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. The number of pupils in the class is?

A - 20

B - 73

C - 40

D - 10

Answer - D

Explanation

Let there be z pupils in the class. 
Total increase in marks = z x 12 = z2 
Therefore z2 = (83 - 63) = z2 = 20 z = 40.

Q 9 - The average age of 36 students in a group is 14 years. When teacher's age is included to it, the average increases by one. What is the teacher's age in years?

A - 31

B - 36

C - none

D - 51

Answer - D

Explanation

Age of the teacher = (37 x 15 - 36 x 14) years = 51 years.

Q 10 - 3 years ago. the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today. The present age of the baby is ?

A - 3

B - 4

C - 2

D - 1

Answer - C

Explanation

Total age of 5 members, 3 years ago = (17 x 5) years = 85 years 
Total age of 5 members now = (85 + 3 x 5) yrs = 100 years 
Total age of 6 members now = (17 x 6) years = 102 years 

Therefore Age of younger child = (102 - 100) = 2 years

aptitude_averages.htm

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