Question

Seven years ago, the ratio of the ages of A and B was 4 : 5. Eight years hence, the ratio of the ages of A and B will be 9 : 10. What is the difference between their present ages in years ?
1. 2
2. 6
3. 3
4. 4

Answer 1

Correct Answer - Option 3 : 3

Given:

Seven years ago the ratio of ages of A and B = 4 : 5

After 8 years from present the ratio of ages of A and B = 9 : 10

Calculation:

Seven years ago the ratio of ages of A and B

⇒ 4x : 5x

Ratio of Present ages of A and B

⇒ 4x + 7 : 5x + 7

After 8 years the ratio of ages of A and B

⇒ (4x + 7 + 8) : (5x + 7 + 8) = 9 : 10

⇒ 40x + 150 = 45x + 135

⇒ 5x = 15

⇒ x = 3

Difference of present ages of A and B

⇒ (5 × 3 + 7) - (4 × 3 + 7)

⇒ 3 years

∴ The difference of present ages of A and B is 3 years.