The average of first three numbers is double of the fourth number. If the average of all the four numbers is $12,$ find the $4^{th}$ number.

In a match,the average of runs scored by five players is $49$. If 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 runs of a cricket player of $10$ innings was $32$. How many runs must he score in his next innings so as to increase his average of runs by $4$?

The daily maximum temperature in Delhi,for $7$ consecutive days in $May, 1988$,were $42.7^{\circ} C, 44.6^{\circ} C, 42.0^{\circ} C, 39.1^{\circ} C, 43.0^{\circ} C, 42.5^{\circ} C$ and $38.5^{\circ} C$. Find out the average daily maximum temperature (in $^{\circ} C$).

The sum of three numbers is $98$. If the ratio between the first and second is $2:3$ and between the second and third is $5:8$,then the second number is:

The average of $50$ numbers is $38$. If two numbers $45$ and $55$ are discarded,the average of the remaining set of numbers is: