The ratio of the age of a son after 15 years and the present age of his father is 2 : 3. 5 years ago, the age of the father was 4 times the age of the son. The present ages (in years) of the father and the son, respectively, are:

Question

Question

This question was previously asked in

RRB NTPC Graduate Level CBT-I Official Paper (Held On: 06 Jun, 2025 Shift 3)

Answer 1

Given:

After 15 years, son's age : father's present age = 2 : 3

5 years ago, father's age = 4 × son's age

Let present age of son = x years

Let present age of father = y years

Calculation:

From 1st condition:

Son’s age after 15 years = x + 15

Given: (x + 15) / y = 2 / 3

⇒ 3(x + 15) = 2y

⇒ 3x + 45 = 2y ...(1)

From 2nd condition:

5 years ago: Father’s age = y − 5, Son’s age = x − 5

Given: y − 5 = 4(x − 5)

⇒ y − 5 = 4x − 20

⇒ y = 4x − 15 ...(2)

Substitute (2) into (1):

3x + 45 = 2(4x − 15)

⇒ 3x + 45 = 8x − 30

⇒ 75 = 5x

⇒ x = 15

⇒ y = 4x − 15 = 4(15) − 15 = 45

∴ Present ages are: Father = 45 years, Son = 15 years.