There are 3 members in a family. The average age of the father and mother is 40 years. The average age of the father, mother, and daughter is 30 years. Find the age (in years) of the daughter.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 10.
Average = Sum of the observation/Total observation
The average age of the father and mother = 40 years
The sum of the age of the father and mother = 2 × 40 = 80 years
The average age of the father, mother, and daughter = 30 years
The sum age of the father, mother, and daughter = 3 × 30 years = 90 years
Age of the daughter = 90 - 80 = 10 years