Question

Three years ago, the average age of Raju's family of 4 members was 14 years. Raju's daughter having been born, the average age of Raju's family is the same today. What is the age of his daughter? 
1. 2 years 6 months 
2. 2 years 
3. 1 years 
4. 7 years 
5. None of these

Answer 1

Correct Answer - Option 2 : 2 years 

Given 

The average age of Raju's family 3 years ago = 14 years

Formula Used 

Average = sum of observation/No. of observation

Calculation 

Let the age of his daughter is X years.

Three years ago, sum of ages of all four family members = 14 × 4 = 56 years

Today the total age of the 4 members of the family is

⇒ 56 + (4 × 3) = 68 years

A  girl having been born, the average of the family is same today 14yr

⇒ 14 = (68 + X)/5

⇒ 68 + X = 70

⇒ X = 2

∴ The age of his daughter is 2 years.