The average age of 14 students and their teacher is 20 years. If the teacher is excluded, then their average age is reduced by 1.5 years. Find the age of the teacher.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 41 years.
We know that,
Average = Sum of observations/Number of observations
Now,
The average age of 14 students and their teacher is 20 years
The sum of the age of 14 students and a teacher = 15 × 20 = 300 years
The teacher is excluded then, their average age is reduced by 1.5 years
New average = 20 - 1.5 = 18.5 years
The sum of the age of 14 students = 14 × 18.5 = 259 years
The teacher's age = 300 - 259 = 41 years