Question

A school bus consisting of 40 boys went for a trip. The average age of these 40 boys was 8 years. If the teacher's age is included, the average increased by 1 year. What will be the age of the teacher?
1. 49 years
2. 28 years
3. 17 years
4. 64 years

Answer 1

Correct Answer - Option 1 : 49 years

Given: 

Number of boys = 40

Average of 40 boys = 8 years

Concept:

Average age = Total age of all the boys/ number of boys 

Calculation:

Total age of the boys = Average × number of boys 

⇒ 8 × 40 = 320 

Average after including the age of the teacher = 9 years 

Total age of 40 boys and the teacher = 9 × 41 = 369 years 

Age of the teacher = 369 years - 320 years = 49 years