The average of $6$ numbers is $20 .$ If one number is removed, the average becomes $15 .$ What is the number removed?
$5$
$35$
$112$
$45$
The average weight of three boys $A, B$ and $C$ is $54 \frac{1}{3} \,kg,$ while the average weight of three boys $B , D$ and $E$ is $53 \,kg .$ What is the average weight of $A , B , C , D$ and $E$ ?(in $kg$)
The average salary of the entire staff in an office is $Rs.\, 500$ per day. The average salary of officers is $Rs.\, 750$ and that of non-officers is $Rs. \,$ $250 .$ If the number of officers is $15,$ then find the number of nonofficers in the office?
The average salary, per head, of all the workers of an institution is $Rs.\, 60 .$ The average salary of $12$ officers is $Rs.\, 400$; the average salary, per head, of the rest is $Rs.\,56.$ The total number of workers in the institution is
The average of the first nine integral multiples of $3$ is
The average of $30$ numbers is $15 .$ The average of the first $18$ numbers is $10$ and that of the next $11$ numbers is $20 .$ The last number is