Average Age

Let there be $x$ number of people. Their average age is 28 years. So, the sum of all of their ages is $28x$ .

When a 13 year old boy leaves, the sum of ages of people in the meeting decreases by 13 and becomes $28x - 13$ . The number of people also decreases by 1 and becomes $x - 1$ . The new average age is $28.00745$ .

So, $\frac{28x-13}{x-1} = 28.00745$ .

On solving this equation, we get $x \sim 2014$

say n number of people $$ => total age = 28n $$ after leaving $$ total person is n-1 $$ total age is 28n-13 $$ A/Q $\frac{28n-13}{n-1}=28.00745$ $$ solving we get, n = 2014.42 $$ => take 2014

average age