At present, ratio of age of mother to her daughter is 7 : 1. After 5 years the ratio will be 4 : 1. What is the difference (in years) in their present ages?
Answer & explanation
Correct answer: option 1
Mother : Daughter
7 : 1 ← (present time)
4 : 1 ← (after 5 years)
ATQ,
⇒ \(\frac{7R + 5}{1R + 5}\) = \(\frac{4}{1}\)
⇒ 7R + 5 = 4R + 20
⇒ 3R = 15
⇒ 1R = 5
Therefore, Difference of their present age = 7R - 1R = 6R = 6 × 5 = 30 years