Question

The average age of $24$ boys and a teacher is $15$ . When the teacher' age is excluded the average decreases by $1$. What is the age of the teacher?

• A. $39$ years
• B. $38$ years
• C. $40$ years
• D. $41$ years

Answer 1

The correct option is A $39$ years

Total age of 24 boys and one teacher $=25\times 15$
$=375years$
Average age of 24 boys $=15-1=14years$
$\therefore$ Total age of 24 boys $=24\times 14=336years$
$\Rightarrow$ Teacher's age $=375-336=39years.$