Average Quants MCQs with Answer - Exercise III


Ques 1 Average


A student finds the average of 10, 2 digit numbers. If the digits of one of the numbers is interchanged, the average increases by 3.6. The difference between the digits of the 2-digit numbers is.
  a) 4
  b) 3
  c) 2
  d) 5


a is the correct option
Swapping the digits of a two-digit number changes its value by a multiple of 9 (e.g., 52 - 25 = 27).
The average of 10 numbers increases by 3.6, meaning the total sum increased by 36 (10 x 3.6).
Since the change is a multiple of 9, the difference between the digits of the number must be 4 (36 / 9 = 4).
Therefore, the answer is (a) 4.




Ques 2 Average


Out of four numbers the average of the first three is 16 and that of the last three is 15. If the last number is 20 then the first number is.
  a) 23
  b) 28
  c) 25
  d) 21


a is the correct option




Ques 3 Average


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 (in kg) of B is.
  a) 31
  b) 17
  c) 26
  d) 20


a is the correct option




Ques 4 Average


If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55 and 60, then the average marks of all the students is.
  a) 53.33
  b) 54.68
  c) 55
  d) None of these


b is the correct option




Ques 5 Average


The average marks of 50 students in a class is 72. The average marks of boys and girls in that subject are 70 and 75 respectively. The number of boys in the class is.
  a) 25
  b) 30
  c) 35
  d) 20


b is the correct option




Ques 6 Average


The average of all the numbers between 6 and 50 which are divisible by 5 is.
  a) 28.5
  b) 22
  c) 30
  d) 27.5


d is the correct option