The ratio of the ages of A, B and C, 5 years ago, was 4 : 5 : 7. The sum of their present ages is 135 years. What will be the sum of the ages (in years) of B and C, 3 years from now?

Question

Question

This question was previously asked in

SSC GD 16 Nov 2021 Shift 2 (Official Paper)

Answer 1

Given:

5 years ago, ratio of ages of A, B and C = 4 : 5 : 7.

Sum of their present ages = 135 years.

Concept used:

Total = Average × Number of entities

Calculation:

Let the common ratio be Q.

So, 5 years ago, the ages of A, B, and C are 4Q, 5Q, and 7Q respectively.

Now, their present ages are (4Q + 5), (5Q + 5), and (7Q + 5) respectively.

According to the question,

(4Q + 5) + (5Q + 5) + (7Q + 5) = 135

⇒ 16Q + 15 = 135

⇒ 16Q = 135 - 15

⇒ 16Q = 120

⇒ Q = 7.5

The present age of B = (5 × 7.5 + 5) = 42.5 years

The present age of C = (7 × 7.5 + 5) = 57.5 years

Now, 3 years from now, the sum of the ages of B and C

⇒ (42.5 + 3) + (57.5 + 3)

⇒ 106 years

∴ After 3 years from now, the sum of the ages of B and C will be 106 years.