Answer:
The rooms should be rented at $75 per day for a maximum income of $11250 per day.
Explanation:
If the daily rental is increased by $ x
then
Rental: R (x )=( 40 + x ) dollars per room-day
Number of rooms rented: N ( x ) = ( 220 − 2 x ) and
Income: I ( x ) = ( 40 + x ) ( 220 − 2 x ) =8800+140x-2x² dollars/day
The maximum will be achieved when the derivative of I ( x ) is zero.
x=35
so, ($40+$35)=75$per day
I ( x35) =8800+140(35)-2(35)²= 11250