Question

Ravi’s fathers is 4 times as old.after 20 years,he will be twice the age of his son. Find the present ages

Answer 1

Take note that the age difference between Ravi and his father never changes.

Ratio of Ravi to his father -> 1 : 4

Ratio of Ravi to his father after 20 years -> 1 : 2

Difference -> 4u - 1u = 3u

Difference after 20 years -> 2u - 1u = 1u

Because their age difference never changes, we have to make them the same.

So, Ratio of Ravi to his father after 20 years -> 1 : 2 (x3 to both sides to get 3 : 6)

Ravi : Father -> 1 : 4

Ravi : Father -> 3 : 6 (After 20 years)

3u - 1u = 2u OR 6u - 4u = 2u

2u = 20

1u = 20 / 2 = 10 (Ravi's age)

Ravi's father age = 4u = 10 x 4 = 40.

Ravi is 10 and his father is 40.

Answer 2

Let Ravi's age be x

Let his father's age be 4x


After 20 years, their ages be x + 20 and 4x + 20



A/q,

4x + 20 = 2(x + 20)

4x + 20 = 2x + 40

4x - 2x = 40 - 20

2x = 20

x = $\frac{20}{2}$

x = 10


• Ravi's age => x => 10 years

• Ravi's father's age => 4x => 4 × 10 => 40 years