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:

If the mean of $5$ observations $x, x+2, x+4, x+6$ and $x+8$ is $11,$ then the mean of the last three observations is

Five years ago,the average age of $P$ and $Q$ was $15 \text{ years}$. Now,the average age of $P$,$Q$,and $R$ is $20 \text{ years}$. What will be the age of $R$ after $10 \text{ years}$?

The average of $10$ numbers is $7$. What will be the new average if each of the numbers is multiplied by $8$?

The average marks in English subject of a class of $24$ students is $56$. If the marks of three students were misread as $44, 45$ and $61$ instead of the actual marks $48, 59$ and $67$ respectively,then what would be the correct average?

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