Three $years$ ago,the average age of a family of $5$ members was $17$ $years$. With the birth of a new baby,the average age of the family remains the same even today. Find the age of the baby (in $years$).

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

The average of the squares of the first ten natural numbers is

The average of $6$ numbers is $8$. What is the $7^{th}$ number so that the average becomes $10$?

The average monthly salary of $20$ employees in an organisation is $Rs. 1500$. If the manager's salary is added, then the average salary increases by $Rs. 100$. What is the manager's monthly salary (in $Rs.$)?

The average age of $30$ women decreases by $3$ months if a new person,Neha,is included in place of a $25$ year old woman. Calculate the age of Neha in years.