Fifteen movie theatres average $600$ customers per theatre per day. If $six$ of the theatres close down but the total theatre attendance stays the same,then the average daily attendance per theatre among the remaining theatres is:

In a set of prime and composite numbers,the number of composite numbers is twice the number of prime numbers,and the average of all the numbers in the set is $9$. If the number of prime numbers and composite numbers are exchanged,then the average of the set of numbers increases by $2$. If,during the exchange of the numbers,the average of the prime numbers and composite numbers individually remained constant,then what was the ratio of the average of composite numbers to the average of prime numbers (initially)?

If the average of $6$ consecutive even numbers is $25,$ the difference between the largest and the smallest number is

In an examination,the average marks were found to be $60$. The marks of $80$ candidates had to be changed from $95$ to $70$ each,and the average came down to $55$ marks. The total number of candidates who attended the examination was:

$A$ batsman makes a score of $270$ runs in the $87^{th}$ inning and thus increases his average by a certain number of runs that is a whole number. Find the possible values of the new average.

$A$ batsman scores $98$ runs in the $17^{\text{th}}$ match of his career. His average runs per match increases by $2.5$. What is his average before the $17^{\text{th}}$ match?