$A$ cricketer scored some runs in his continuous $9$ innings. He scored $100$ runs in his $10^{th}$ innings and this increased his average by $8$ runs. What was the average of his runs at the end of $10^{th}$ innings?

The average age of students of a class is $15.8 \, \text{years}$. The average age of boys in the class is $16.4 \, \text{years}$ and that of the girls is $15.4 \, \text{years}$. The ratio of the number of boys to the number of girls in the class is:

Average of $a, b$ and $c$ is $11$; average of $c, d$ and $e$ is $17$; average of $e$ and $f$ is $22$ and average of $e$ and $c$ is $17$. Find out the average of $a, b, c, d, e$ and $f$?

Find the average of first $25$ multiples of $5$.

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?

In an examination,out of $20$ students in a class,in Mathematics $2$ students scored $100$ marks,$3$ students scored $0$,and the average marks for the rest of the students was $40$. What is the average mark of the whole class? (in marks)