The average age of $20$ boys in the class is $15.6$ years. Five new boys join and the new average becomes $15.56$ years. What is the average age of the five new boys (in years)?

The average age of $5$ members is $21 \text{ years}$. If the age of the youngest member is $5 \text{ years}$,find out the average age of the family at the birth of the youngest member (in $\text{years}$).

The average monthly expenditure of a family for the first four months is $Rs. 2750$,for the next three months is $Rs. 2940$,and for the last five months is $Rs. 3130$. If the family saves $Rs. 5330$ throughout the year,find the average monthly income of the family for that year (in $Rs.$).

The average of runs of a cricket player of $10$ innings was $32$. How many runs must he score in his next innings so as to increase his average of runs by $4$?

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 price per $kg$ of rice at $10$ different places was $Rs. 4.85$. After a week,the price per $kg$ was increased by $20$ paise at $3$ places and decreased by $10$ paise at $1$ place. What is the new average price per $kg$ in $Rs.$?