A group of 36 students has an average present age of 14 years. When the age of the teacher is included, the average age rises by one. Calculate the teacher's age (in years).
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 51.
Average = Sum of observations/Number of observations
Let the teacher's age be x years
According to the given question,
Sum of ages of 36 students = 36 × 14 = 504
Now,
504 + x = 37 × 15
⇒ 504 + x = 555
⇒ x = 555 - 504
⇒ x = 51
Hence, the teacher's age is 51 years