model 4 find nth average from 1st & last number Practice Questions Answers Test with Solutions & More Shortcuts

Question : 6 [SSC CGL Tier-I 2014]

The average of 11 numbers is 63. If the average of first six numbers is 60 and the last six numbers is 65, then the 6th number is

a) 60

b) 64

c) 62

d) 57

Question : 7

Average of n numbers is a. The first number is increased by 2, second one is increased by 4, the third one is increased by 8 and so on. The average of the new numbers is

a) a+2 ${2^{n} – 1}/n$

b) a+${2^{n }- 1}/n$

c) a+$2^{n-1} /n$

d) a+${2^{n-1} – 1}/n$

Question : 8

The average of nine numbers is 50. The average of the first five numbers is 54 and that of the last three numbers is 52. Then the sixth number is

a) 34

b) 44

c) 24

d) 30

Question : 9

The average of 8 numbers is 20. The average of first two numbers is 15$1/2$ and that of the next three is 21$1/3$. If the sixth number be less than the seventh and eighth numbers by 4 and 7 respectively, then the eighth number is :

a) 22

b) 27

c) 25

d) 18

Question : 10 [SSC MTS (NT) 2011]

The average of three numbers is 135. The largest number is 195 and the difference between the other two is 20. The smallest number is

a) 95

b) 115

c) 105

d) 65