The average of marks obtained by $120$ candidates was $35.$ If the average of marks of passed candidates was $39$ and that of failed candidates was $15,$ the number of candidates who passed the examination is

The average age of a group of $15$ students is $10 \, \text{years}$. When $5$ more students joined the group,the average age increased by $1 \, \text{year}$. If the average age of the $5$ new students is $x$,find the value of $x$ (in $\text{years}$).

In an examination,the average marks obtained by the girls of a class is $85$ and the average marks obtained by the boys of the same class is $87$. If the girls and boys are in the ratio $4:5$,the average marks of the whole class (approx.) is closest to:

The average of two numbers $A$ and $B$ is $20,$ that of $B$ and $C$ is $19,$ and that of $C$ and $A$ is $21.$ What is the value of $A?$

The average of three numbers is $135$. The largest number is $195$ and the difference between the other two is $20$. The smallest number is:

The average weight of $8$ persons increases by $2.5\, kg$ when a new person comes in place of one of them weighing $65\, kg$. What is the weight of the new person? (in $kg$)