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

The average age of $8$ men is increased by $2\,years$ when two of them whose ages are $21\, years$ and $23\, years$ are replaced by two new men. The average age of the two new men is

The average monthly salary of all the employees in an industry is $Rs.\, 12,000$. The average salary of male employees is $Rs.\,15,000$ and that of female employees is $Rs.\, 8,000 .$ What is the ratio of male employees to female employees?

Average age of $15$ students of a class is $15\, years.$ Out of these the average age of $5$ students is $14 \,years$ and that of the other $9$ students is $16\, years.$ The age of the $15^{th}$ student is (in $years$)

The average weight of $36$ students is $50 \,kg$. If was found later that the weight of one of the student was misread as $73 \,kg$. whereas his actual weight was $37 \,kg$. Find the correct average. (in $kg$)

The average expenditure of a man for the first five months is $Rs.\, 120$ and for the next seven months is $Rs. \,130$ . His monthly average income in $Rs.$ if he saves $Rs. \,290$ in that year, is