# 1000+ TNPSC Maths Aptitude Previous Year Questions - 1

Question: 1

The average of the reciprocals of x and y is

(A) $${(x + y)}/{(x - y)}$$

(B) $${(x + y)}/{2xy}$$

(C) $${2(x + y}/{xy}$$

(D) $${2xy}/{(x + y)}$$

Ans: B

Required average = $${(1/x + 1/y)} / {2}$$ = $${x + y}/{2xy}$$

Question: 2

The average of five numbers is 58. The average of the first two numbers is 48.5 and the average of last two number is 53.5. What is the third number.

(A) 56

(B) 66

(C) 76

(D) 86

Ans: D

Third number = (Sum of 5 numbers) - (Sum of 4 numbers)

= (58 × 5) - [(48.5 × 2) + (53.5 × 2)]

= 290 - (97 + 107) = 290 - 204 = 86.

Question: 3

The average age of a group of persons going for picnic is 16 years. Twenty new persons with an average age of 15 years join the group on the spot due to which their average age becomes 15.5 years. The number of persons initially going for picnic is

(A) 10

(B) 20

(C) 30

(D) 40

Ans: B

Let the initial number of persons be x. Then,

16x + 20 ×15 = 15.5(x + 20) ⇒ 0.5x = 10 ⇒ x = 20.

Question: 4

The average temperature for the first four days of a week is 40.2°C and that of the last four days is 41.3°C. If the average temperature for the whole week is 40.6°C, then the temperature on the fourth day is

(A) 38.5°C

(B) 41.3°C

(C) 41.5°C

(D) 41.8°C

Ans: D

Temperature on the fourth day

= [(40.2 × 4 + 41.3 × 4) - (40.6 × 7)]°C = 41.8°C.

Question: 5

Four years ago, the average age of A and B was 18 years. At present the average age of A, B and C is 24 years. What would be the age of C after 8 years?

(A) 25 years

(B) 28 years

(C) 36 years

(D) 38 years

Ans: C

Sum of the present ages of A and B

= (18 × 2 + 4 × 2) years = 44 years.

Sum of the present ages of A, B and C

= (24 × 3) years = 72 years.

C’s present age = (72 - 44) years = 28 years.

∴ C’s age after 8 years = (28 + 8) years = 36 years.

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