If the average of the ages of Rakesh and Mohan is $15$,the average of the ages of Mohan and Ramesh is $12$,and the average of the ages of Rakesh and Ramesh is $13$,then what is the age of Mohan?

The average marks obtained by $40$ students of a class is $86$. If the $5$ highest marks are removed,the average reduces by $1$ mark. The average marks of the top $5$ students is

The average salary of workers in $AMS$ careers is $Rs. 2,000$,the average salary of faculty is $Rs. 4,000$,and the average salary of management trainees is $Rs. 1,250$. The total number of workers could be:

The average weight of a group of $20$ boys was calculated to be $89.4 \text{ kg}$ and it was later discovered that one weight was misread as $78 \text{ kg}$ instead of the correct one of $87 \text{ kg}$. The correct average weight is in $\text{kg}$.

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

Three years ago,the average age of a family of $5$ members was $27 \text{ years}$. After the addition of a child to the family,the present average age of the family is still $27 \text{ years}$. Find the present age of the child (in years).