A batsman score $98$ runs in the $17^{\text {th }}$ match of his career. His average runs per match increase by $2.5$ What is his average before the $17^{\text {th }}$ match?

The average weight of $3 \operatorname{men} A, B$ and $C$ is $84\, kg.$ Another man $D$ joins the group and the average now becomes $80 \,kg .$ If another man $E ,$ whose weight is $3 \,kg$ more than that of $D ,$ replaces $A,$ then the average weight of $B, C, D$ and $E$ becomes $79 \,kg .$ The weight of $A$ is (in $kg$)

The average age of $30$ women decreases by $3$ $months$ if a new person Neha is included in place of a $25\, year$ old woman. Calculate the age of Neha in $year$ ?

The average age of $6$ members of a family is $20\, years.$ If the age of a servant is included, the average age increased by $25 \%$. What is the age (in $years$) of the servant ?

The average of $7$ consecutive numbers is $20 .$ The largest of these numbers is

In a school with $600$ students, the average age of the boys is $12$ $years$ and that of the girls is $11\, years.$ If the average age of the school is $11 \,years$ and $9 \,months,$ then the number of girls in the school is