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:

The average age of $24$ boys and their teacher is $15 \text{ years}$. When the teacher's age is excluded,the average age decreases by $1 \text{ year}$. What is the age of the teacher in years?

The daily earnings of a taxi driver during a week are: $Rs. 60, Rs. 65, Rs. 70, Rs. 52.50, Rs. 63, Rs. 73,$ and $Rs. 68$. What is his average daily earning for the week (in $.50$)? (in $Rs.$)

The average weight of all the $11$ players of the Indian cricket team is $50 \, kg$. If the average weight of the first six lightest players is $49 \, kg$ and that of the six heaviest players is $52 \, kg$,find the weight of the player who is in the sixth position when all $11$ players are arranged in order of increasing weights (in $kg$).

The average of runs scored by a cricketer in his $99$ innings is $99$. How many runs will he have to score in his $100^{\text{th}}$ innings so that his average of runs in $100$ innings may be $100$?

The average of $6$ numbers is $20$. If one number is removed, the average becomes $15$. What is the number removed?