The average of the first nine integral multiples of $3$ is

The average of $12$ results is $15,$ and the average of the first two is $14.$ What is the average of the rest?

The average age of a committee of $8$ members is $40 \,years.$ A member, aged $55\, years,$ retired and he was replaced by a member aged $39\, years.$ The average age of the present committee is (in $years$) 

Sachin Tendulkar has a certain average for $11$ innings. In the $12^{th}$ innings he scores $120$ runs and thereby increases his average by $5$ runs. His new average is

A librarian purchased $50$ $story-books$ for his library. But he saw that he could get $14$ more books by spending $Rs.\, 76$ more and average price per book would be reduced by $Rs.\,1.$ The average price (in $Rs.$) of each book he bought, was

The average of $30$ numbers is $15 .$ The average of the first $18$ numbers is $10$ and that of the next $11$ numbers is $20 .$ The last number is