The average age of $8$ men is increased by $2\, years.$ When $2$ of them, whose ages are $20\, years$ and $24 \,years$ respectively, are replaced by $2$ women. What is the average age of these two women ? (in $years$)
$36$
$30$
$40$
$42$
A cricketer gives $12.4$ runs per wicket. He gives $26$ runs and takes $5$ wicket in a match after which his average becomes $12$ per wicket. How many wickets had been taken till the last match?
Average age of $A, B$ and $C$ is $84\, years.$ When $D$ joins them the average age becomes $80\, years.$ A new person, $E,$ whose age is $4 \,years$ more than $D,$ replaces $A$ and the average of $B, C, D$ and $E$ becomes $78\, years.$ What is the age of $A$ ? (in $years$)
The arithmetic mean of the following numbers is $1,2,2,3,3,3,4,4,4,4,5,5,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,7$
The mean weight of $150$ students in a class is $60 \,kg.$ The mean weight of boys is $70\, kg$ and that of girls is $55 \,kg$. What is the number of boys in the class?
Amitabh's average expenditure for the $January$ to $June$ is $Rs.\, 4200$ and he spends $Rs.\, 1200$ in $January$ and $Rs. \,1500$ in $July.$ The average expenditure for the month of $February$ to $July$ is (in $Rs.$)