Question 10

The average age of 19 boys in a class is 21 years. If the teacher's age is included, the average increases to 22 years. What is the teacher's age?

Solution

Average age of 19 boys = 21 years

=> Total age of 19 boys = $$21\times19=399$$ years

Let age of teacher = $$x$$ years

Average of class including teacher = $$\frac{399+x}{20}=22$$

=> $$399+x=22\times20=440$$

=> $$x=440-399=41$$ years

=> Ans - (B)

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