Ten years ago the average age of $P$ and $Q$ was $20\, years.$ Average age of $P, Q$ and $R$ is $30\, years$ now. After $10 \,years,$ the age of $R$ will be (in $years$)

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

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

The average weight of all the $11$ players of Indian cricket team is $50\, kg.$ If the average of first six lightest weight players is $49\, kg$ and that of the six heaviest players is $52\, kg$. The average weight of the player which lies in the sixth position in the list of players when all the $11$ $players$ are arranged in the order of $increasing$ or $decreasing$ $weights$ (in $kg$)

Find average of all prime numbers between $60$ and $90.$

Sachin Tendulkar has a certain average for $11$ innings. In the $12^{th}$ innings he scores $120$ runs and thereby increases his average by $5$ runs. His new average is