Question

The average age of 30 boys in a class is 10 years. If the age of their teacher is also included, the average increases by one year The teacher's age in years is

1. 38
2. 40
3. 30
4. 41

Answer 1

Correct Answer - Option 4 : 41

Given

The average age of 30 boys in a class is 10 years. If the age of their teacher is also included, the average increases by one year

Formula used

Average = total sum of observation/number of observation

Calculation

Total sum of age of 30 boys = 10 × 30 = 300 years

⇒ After adding teacher new average = 11 years

⇒ New sum = 11 × 31 = 341 years

∴ Teacher's age is 341 - 300 = 41 years