The average of $13$ results is $60$. If the average of the first $7$ results is $59$ and that of the last $7$ results is $61$,what will be the seventh result?

Out of four numbers,the average of the first three is $16$ and that of the last three is $15$. If the last number is $20$,then the first number is:

The average daily wages of $A, B$ and $C$ is $Rs. 120$. If $B$ earns $Rs. 40$ more than $C$ per day and $A$ earns double of what $C$ earns per day,the wages of $A$ per day is (in $Rs.$)

The average marks obtained by $150$ students in an examination is $40$. If the average marks of passed students is $60$ and that of the failed students is $20$,what is the number of students who passed the examination?

The mean of marks secured by $50$ students in division $A$ of class $X$ is $61$,$25$ students of division $B$ is $57$,and that of $50$ students of division $C$ is $55$. What will be the mean of marks of the students of three divisions of Class $X$?

The average age of $35$ students in a class is $16$ years. The average age of $21$ students is $14$ years. What is the average age of the remaining $14$ students (in years)?