Question

The average age of 20 students of a class is 18 . When the ate if class teacher is included the average age becomes 20. Find the age of class teacher.

Answer 1

Average age of 20 students is 18

Total age of the class = 18 × 20 = 360

Suppose teacher's age is x
So, ( 360 + x ) ÷ 21 = 20
360 + x = 20 × 21
360 + x = 420
x = 420 - 360 = 60
The teacher's age is 60 years .


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