Question

Average age of a group of 10 students is 12 years. If 5 new students join them, then the average age of the group increases by 1 years. The average age of the new students is
1. 13 years
2. 15 years
3. 16 years
4. 18 years

Answer 1

Correct Answer - Option 2 : 15 years

Given:

The average age of 10 students is 12 years.

If 5 new students joined with them average age of the group increase by 1 years

Concept Used:

Sum = Average × Number of observations

Calculation:

Previously sum of ages of 10 students = 10 × 12 = 120 years

Present average age = (12 + 1) = 13 years

Present sum of ages of 15 boys = (13 × 15) = 195 years

⇒ The Sum of ages of 5 students is (195 - 120) = 75 years

Average age of new students = 75/5 = 15 years

∴ The average age of the new students is 15 years.