A class has $20$ boys and $30$ girls. The average age of boys is $11\, years $ and that of girls is $12\,years.$ What is the average age of the whole class in $year$
$11.6$
$12$
$10$
$11.2$
$16$ children are to be divided into two groups $A$ and $B$ of $10$ and $6$ children. The average percent marks obtained by the children of group $A$ is $75$ and the average per cent marks of all the $16$ children is $76 .$ What is the average per cent marks of children of group $B$ ?
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 of the first nine integral multiples of $3$ is
Of the $3$ members whose average is $22 .$ What is the first number ?
The average temperature from Monday to Thursday is $48^{\circ} C$ and from Tuesday to Friday is $52^{\circ} C$. If the temperature on Monday is $42^{\circ} C$, what was it on Friday? (in $^{\circ} C$)