The average age of 10 students and their class teacher is 17 years. If the age of the class teacher is excluded, the average age of the 10 students is reduced by 2 years. What is the age of the class teacher?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 37 years.
The average age of 10 students and their class teacher is 17 years.
Average = (Sum of all the observations/Number of observations)
The sum of the age of 10 students and their teacher = 11 × 17 = 187 years
The sum of the age of 10 students = 10 × (17 - 2) = 150 years
The age of teacher = 187 - 150 = 37 years