Average

If the weight of $18$ sheets of paper is $50 g$, then how many sheets of the same paper will weight $3\frac{3}{4} kg$?

There are three sections $A, B$ and $C$ in Class $X$ with $25, 40$ and $35$ students, respectively. The average marks obtained by sections  $A, B$and $C$ are ,$70, 65$ and $50$, respectively. The average marks of entire Class $X$ is _________.

The average age of $25$ boys in a class decreases by $6$ months, when a new boy takes the place of a $20 yr$ boy. Find the age of new boy.

In a cricket team, the average age of $11$ players and the coach is $18 yr$. If the age of the coach is not considered, then the average decreases by $1 yr$. Find out the age of coach.

The average age of Ram, Hari and Gopal is $42 yr$. If their ages are in the ratio of $2:3:4$ respectively, then what is the age (in years) of Hari?

The average age of a brother and sister was $35 yr$, $5 yr$ ago. What will be their average age (in years) at present?

The average age of five officers in a department is $32 yr$. If the age of their supervisor is added the average increased by $1$. What is the supervisor's age?