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?

The average of the first $100$ positive integers is

The average salary per head of all the workers in a company is $Rs. \,95$. The average salary of $15$ officers is $Rs. \,525$ and the average salary per head of the rest is $Rs. \,85$. Find the total number of workers in the workshop.

The average weight of $4$ men $A, B, C,$ and $D$ is $67 \, kg.$ When a $5^{th}$ man $E$ is included,the average weight decreases by $2 \, kg.$ $A$ is replaced by $F.$ The weight of $F$ is $4 \, kg$ more than $E.$ The average weight decreases because of the replacement of $A,$ and now the average weight is $64 \, kg.$ Find the weight of $A.$

$A$ professional institute's total expenditure on students for a particular course is partly fixed and partly varies linearly with the number of students. The average expense per student is $Rs.\,615$ when there are $24$ students and $Rs.\,465$ when there are $40$ students. What is the average expense when there are $60$ students? (in $Rs.$)

The average of the first $9$ integral multiples of $3$ is