A 300 room hotel in Guatemala is filled to capacity every ni
     A 300 room hotel in Guatemala is filled to capacity every night at a rate of $80 per room. For each $1 increase in the nightly rate. 3 fewer rooms are rented. If each rented room costs $10 a day to service, how much should the management charge per room in order to maximize gross profit? What is this maximum profit?  The price-demand equation for a fancy watch is given by p(x) = 1200e^-0.01x. where x represents the monthly demand and p is the price in dollars. Find the production level, x. and price per unit, p. that produce the maximum revenue. What is this maximum revenue? 
  
  Solution
Solution : (3)
a )
Let x be the amount over $80 for a room.
When x = 0, the hotel rents 300 rooms.
When x = 1, the hotel rents 300 – 3 = 297 rooms
When x = 2, the hotel rents 297 – 3 = 294 rooms
Number of rooms rented = N(x) = 300 – 3x
Profit per room = (rent earned) – (cleaning costs)
R(x) = (80 + x) – 10 = 70 + x
Total Profit = P(x) = N(x) R(x) = (300 – 3x)(70 + x)
P(x) = -3x2 + 90x + 21000
P(x) = -3x2 + 90x + 21000
P’(x) = -6x + 90
Set P’(x) = 0
to find x = 15.
The room charge should be $95.
Number of rooms rented
= 300 – 3(15) = 265
Total profit P(15) = $21675.

