Question

The average age of 40 pupils in a class is 10.5. If the class teacher is included , the average increases by 5.Then the age of the class teacher is

• A. 37
• B. 36
• C. 31
• D. 40

Answer 1

Answer:

C. 31

Average age of 40 pupils (= 10.5)

So, total age of pupils:

$40 \times 10.5 = 420$

When the teacher is included, the average increases by 5:

$10.5 + 5 = 15.5$

Now total persons (= 41)

Total age including teacher:

$41 \times 15.5 = 635.5$

Teacher’s age:

$635.5 - 420 = 215.5$

So, the age of the class teacher is 215.5 years, which is not realistic.
This means the question likely has a mistake.

If the intended statement was “average increases by 0.5”, then:

$41 \times 11 = 451$

Teacher’s age:

$451 - 420 = 31$

So the likely correct answer is 31 years.