model 1 basic average questions Section-Wise Topic Notes With Detailed Explanation And Example Questions

Question : 1

The average of marks obtained by 100 candidates in a certain examination is 30. If the average marks of passed candidates is 35 and that of the failed candidates is 10, what is the number of candidates who passed the examination?

a) 80

b) 90

c) 70

d) 60

Question : 2

The average of 30 numbers is 15. The average of the first 18 numbers is 10 and that of the next 11 numbers is 20. The last number is

a) 60

b) 50

c) 52

d) 56

Question : 3

A student was asked to find the arithmetic mean of the following 12 numbers : 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x He found the mean to be 12. The value of x will be :

a) 17

b) 31

c) 7

d) 3

Question : 4

The average marks of 32 boys of section A of class X is 60 whereas the average marks of 40 boys of section B of class X is 33. The average marks for both the sections combined together is

a) 46$1/2$

b) 45$1/2$

c) 45

d) 44

Question : 5

The average weight of 8 persons increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg. The weight of the new person is

a) 76 kg

b) 76.5 kg

c) 85 kg

d) 84 kg

Question : 6

If average of 20 observations $x_1 , x_2 , ....., x_20$ is y, then the average of $x_1 – 101, x_2 – 101, x_3 – 101, ....., x_20 –101$ is

a) 20y

b) 101y

c) y – 101

d) y – 20