The average of $20$ numbers is $30$ and that of other $30$ numbers is $50 .$ What is the average of all the numbers.

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

The average salary of $20$ workers in an office is $Rs.\, 1900$ per $month.$ If the manager's salary is added, the average becomes $Rs.\,2000$ per $month.$ The manager's annual salary (in $Rs.$) is

The average salary per head of all workers of an institution is $Rs. \,60\,.$ The average salary per head of $12$ officers is $Rs. \,400 .$ The average salary per head of the rest is $Rs.$ $56 .$ Then, the total number of workers in the institution is?

The average annual income (in $Rs.$) of certain agricultural workers is $S$ and that of other workers is $T$. The number of agricultural workers is $11$ times that of other workers. Then the average annual income (in $Rs.$) of all the workers is

The average marks obtained by a class of $60$ students is $05.$ The average marks of half of the students is found to be $85 .$ The average marks of the remaining students is