Question

The average age of 40 pupils in a class is 10.5. If the class teacher is included , the average increases by 0.5.Then the age of the class teacher is

• A. 37
• B. 36
• C. 31
• D. 40

Answer 1

Answer:

C. 31

The age of the class teacher is 31 years.

Shortcut Method

You can also solve this quickly using the deviation method:

• $\text{Teacher's Age} = \text{New Average} + (\text{Previous Number of People} \times \text{Increase in Average})$

• $\text{Teacher's Age} = 11 + (40 \times 0.5) = 11 + 20 = \mathbf{31\text{ years}}$