The mean of marks secured by $50$ students in division $A$ of class $X$ is $61,\,25$ students of division $B$ is $57$ and that of $50$ students of division $C$ is $55 .$ What will be the mean of marks of the students of three divisions of Class $X$ ?
$57.1$
$56.4$
$59.2$
$57.8$
Fifteen movie theatres average $600$ customers per theatre per day. If $six$ of the theaters close down but the total theater attendance stays the same, then the average daily attendance per theatre among the remaining theaters is
The sum of five consecutive integers is $a$ and the sum of next five consecutive integers is $b$. Then $\frac{(b-a)}{100}$ is equal to
The average salary of the entire staff in an office is $Rs.\, 500$ per day. The average salary of officers is $Rs.\, 750$ and that of non-officers is $Rs. \,$ $250 .$ If the number of officers is $15,$ then find the number of nonofficers in the office?
The average of $5$ quantities is $6 .$ The average of three of them is $8 .$ What is the average of remaining two quantities?
The average age of $24$ boys and their teacher is $15 \,years.$ When the teacher's age is excluded, the average age decreases by $1\, year.$ The age of the teacher is in $years$ ?