Problems on Ages Quiz Set 012

Question 1

The sum of the ages of 12 calves of a whale born at a gap of 8 years is 672. What is the age of the youngest calf?

A

12 years.

B

13 years.

C

11 years.

D

14 years.

Soln.
Ans: a

The ages of the calves are in an AP with d = 8, n = 12, and sum S = 672. We have to find the first term a. We know S = \${n/2} × (2a + (n-1)d)\$ Putting the values 672 = \${12/2} × (2a + (12-1)×8)\$. Solving, get a = 12 years.

Question 2

Mr. X became a voter at the age of 18. He got married at the age of 24. What was his average age during these two points of his life?

A

21 years.

B

22 years.

C

20 years.

D

6 years.

Soln.
Ans: a

The average is simply \${18 + 24}/2\$ = 21 years.

Question 3

The ages of three friends are in the ratio 3:7:5. What is the age of the youngest friend if the sum of their ages 6 years back was 57 years?

A

15 years.

B

16 years.

C

14 years.

D

17 years.

Soln.
Ans: a

Let the ages of three friends be 3r, 7r and 5r. The youngest of these is 3r. We have been given their sum 6 years back. So (3 + 7 + 5)r - (3 × 6) = 57. Solving, we get r = 5. The youngest is 3 × 5 = 15 years.

Question 4

The ratio of present ages of two monuments A and B is \$3{2/5}\$. If the difference of their ages is 120, then what is the age of B?

A

50 years.

B

45 years.

C

40 years.

D

55 years.

Soln.
Ans: a

The ratio of ages of A and B is given as \${17/5}\$, which is same as: \$3{2/5}\$. So we can write the present ages of A and B, respectively, as 17r and 5r years. The difference is \$17r - 5r = 120\$ which gives r = 10. The age of B, therefore, is 5r = 5 × 10 = 50 years.

Question 5

The ages of two friends are 3 and 27 years respectively. They are looking for a special third friend whose age is in-between their ages. What should be the age of the third friend if the ages of all three have to be in a GP(geometric progression)?

A

9 years.

B

10 years.

C

8 years.

D

11 years.

Soln.
Ans: a

If the age of the third friend is x. Then for a GP, x = \$√(3 × 27)\$ = 9 years.