The average age of a father and a mother is 35 years. The average age of the father, the mother and their daughter is 25 years. What is the age of their daughter?

5 years

Formula used = Total sum of all observation / Total number of observation

Average age of a father and a mother is 35 years

Sum of age of Mother and Father ( F + M )  = 35 × 2 = 70 years    ----(1)

Average age of the father, the mother and their daughter is 25 years

Sum of age of the father, the mother and their daughter ( F + M + D )  = 25 × 3 = 75 years    ---(2)

By putting sum of age of Mother and Father from Equation 1 in Equation 2 ,

( 70+ D ) = 75

D = 5 years

So , Age of Daughter is 5 years

The correct answer is Option (4) → 5 years