The average weight of five persons sitting in a boat is $38\, kg$. The average weight of the boat and the persons sitting in the boat is $52\, kg$. What is the weight of the boat (in $kg$)?

The average weight of $21$ boys was recorded as $64 \, kg$. If the weight of the teacher was added,the average increased by $1 \, kg$. What was the teacher's weight (in $, kg$)?

The average age of $10$ men is increased by $2 \, \text{years}$ when one of them, aged $25 \, \text{years}$, is replaced by a new man. What is the age of the new man (in $\text{years}$)?

The average of four consecutive odd numbers is $40$. What is the largest number?

The average of $50$ numbers is $38$. If two numbers,namely,$45$ and $55$ are discarded,what is the average of the remaining numbers (in $.5$)?

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 $Rs.$)