$A$ librarian purchased $50$ storybooks for his library. He realized that he could get $14$ more books by spending $Rs. 76$ more,and the average price per book would be reduced by $Rs. 1$. What was the average price (in $Rs.$) of each book he initially bought?

The average monthly expenditure of a family for the first four months is $Rs.\, 2570$,for the next three months $Rs.\, 2490$ and for the last five months $Rs.\, 3030$. If the family saves $Rs.\, 5320$ during the whole year,the average monthly income of the family during the year is (in $Rs.$)

The average of five consecutive positive integers is $n$. If the next two integers are also included,the average of all these integers will

$3 \, \text{years}$ ago,the average age of a family of $5 \, \text{members}$ was $17 \, \text{years}$. With the birth of a new baby,the average age of the $6 \, \text{members}$ remains the same even today. Find the age of the new baby in years.

The average weight of $8$ persons increases by $2.5\, kg$ when a new person comes in place of one of them weighing $65\, kg$. What is the weight of the new person? (in $kg$)

$A$ student was asked to find the arithmetic mean of the numbers $3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14$ and $x$. He found the mean to be $12$. What should be the number in place of $x$?