Average of $a, b$ and $c$ is $11 ;$ average of $c, d$ and $e$ is $17 ;$ average of $e$ and $f$ is $22$ and average of $e$ and $c$ is $17 .$ Find out the average of $a, b,$ $c , d , e$ and $f ?$

The average of four consecutive odd numbers is $40 .$ What is the largest number?

There were $35$ students in a hostel. If the number of students increases by $7,$ the expenses of the mess increase by $Rs. \,42$ per $day$ while the average expenditure per head decreases by $Rs.\, 1 .$ Find the original expenditure of the mess in $Rs.$

The average age of a class of $30$ students and a teacher reduce by $0.5 \,years$ if we exclude the teacher. If the initial average is $14 \,years,$ find the age of the class teacher in $year$ ?

In a match, average of runs scored by five players is $49.$ It the runs scored by four players are $75,30,$ $63$ and $21$ respectively, then how many runs did the fifth player score?

The average of three numbers is $154 .$ The first number is twice the second and the second number is twice the third. The first number is