### Question

**The average age of a class of 22 students is 21 years. The average increased by 1 when the teacher’s age also included. What is the age of the teacher?**

A. 44

B. 48

C. 45

D. 43

#### Answer: A. 44

**Solution:**

Total age of students = 22 × 21

Total age of students + age of teacher =23 × 22

Age of the teacher

= 23 × 22 − 22 × 21

= 22 (23 − 21)

= 22 × 2

**= 44**

Hence, The age of the teacher is **44.**