Question

The average age of a class of $30$ students is $18$; when the teacher is included the average age becomes $19$. What is the age of the teacher?

Answer 1

Let A be the no. of students in a

class then

$\frac{A}{30}=18$

$A=18\times 30$

$A=540$

Let B be the teacher which is included

in the class

$\frac{(A+B)}{30+1}=(18+1)$

$\frac{540+B}{31}=19$

$540+B=\left(19\right)31$

$B=589-540$

$B=49$