The ratio of father's age to the son's age is 4 : 1. The product of their ages is 196. the ratio of their ages after 5 years will be?

Let father's age be 4T and son's age T years.
∵ 4T x T = 196
⇒ T² = 49
∴ T = 7
Father's age after 5 years = (4T + 5) = 33 years
Son's age after 5 years = (T + 5) = 12 years
∴ Ratio of their ages after 5 years = 33 : 12 = 11 : 4