The average age of 30 students in a group is 18 years. When the teacher's age is included, the average age of the group increases by 1 year. What is the teacher's age (in years)?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 49.
Sum of ages of 30 students = 30 × 18 = 540
With teacher: average = 19 → total = 31 × 19 = 589
Teacher’s age = 589 − 540 = 49