At present, ratio of age of mother to her daughter is 5 : 3 . After 30 years the ratio will be 4 : 3 . What is the difference (in years) in their present ages?
Answer & explanation
Correct answer: option 2
Mother : Daughter
5 : 3 ← (present time)
4 : 3 ← (after 30 years)
ATQ,
⇒ \(\frac{5R + 30}{3R + 30}\) = \(\frac{4}{3}\)
⇒ 15R + 90 = 12R + 120
⇒ 3R = 30
⇒ 1R = 10
Therefore, Difference of their present age = 5R - 3R = 2R = 2 × 10 = 20 years