RRB Group-D Model Paper 11 with answers for online practice

Let the age of father be F and that of son be S.

F + S = 50 (Given)

S = 50 – F _____ (i)

Six years back father's age was 6 more than thrice his son's age.

According to problem:

(F – 6) = 3(S – 6) + 6 _____ (ii)

Substituting the value of equation (i) in (ii), we get:

F – 6 = 3(50 – F – 6) + 6

⇒ F – 6 = 3(44 – F) + 6

⇒ F – 6 = 132 – 3F + 6

⇒ F + 3F = 132 + 6 + 6

⇒ 4F = 144

⇒ F = 144/4

⇒ F = 36

So, father's age 6 years hence = (36 + 6) = 42

Hence, ‘42’ is the correct answer.