100+ TNPSC Aptitude Questions and Answers Pdf - 1

Ans: B

A.M. of 75 numbers = 35.

Sum of 75 numbers = (75 × 35) = 2625.

Total increase = (75 × 5) = 375.

Increased sum = (2625 + 375) = 3000.

Increased average = $${3000}/{75}$$ = 40.

Ans: C

Sum of the ages of 4 members, 4 years ago = (18 × 4) years = 72 years.

Sum of the ages of 4 members now = (72 + 4 × 4) years = 88 years.

Sum of the ages of 5 members now = (18 × 5) years = 90 years.

∴ Age of the baby = (90 - 88) years = 2 years.

Ans: D

Average of 12 number = 15

Total of 12 number = 15 × 12 = 180

Average of first two number = 14

Total of first two number = 14 × 2 = 28

Total of remaining ten numbers = 180 - 28 = 152.

Required average of remaining ten number = $${152}/{10}$$ = $${76}/{5}$$ = $$15{1}/{2}$$

Ans: A

Average of 6 numbers = 7

Sum of 6 numbers = 6 × 7 = 42

Average of three numbers = 5

Sum of three numbers = 5 × 3 = 15

∴ Sum of the remaining three numbers = 42 – 15 = 27

∴ Required average = $${27}/{3}$$ = 9.

Ans: D

Sum of first n natural numbers = $${n(n+1)}/{2}$$

So, sum of first 40 natural numbers = $${40 × 41} / {2}$$= 820.

∴ Required average = $${820}/{40}$$ = 20.5.