The mean marks of $10$ boys in a class is $70 \%$,whereas the mean marks of $15$ girls is $60 \%$. The mean marks of all the $25$ students is

The average of the first $25$ numbers is $10$ and the average of the next $25$ numbers is $12$. The average of all $50$ numbers is:

Out of four numbers,the average of the first three is $16$ and that of the last three is $15$. If the last number is $20$,then the first number is:

Out of $30$ teachers of a school,a teacher of age $60$ $years$ retired. In his place another teacher of age $30$ $years$ was appointed. As a result,the mean age of the teachers will

If the average of $m$ numbers is $n^{2}$ and that of $n$ numbers is $m^{2},$ then the average of $(m + n)$ numbers is

In the first $30$ overs of a cricket match,the run rate was $5.2 \text{ runs/over}$. What is the required run rate in the remaining $20$ overs to reach the target of $280$ runs?