A coffee vendor at a popular mall analyzes her records and f
     A coffee vendor at a popular mall analyzes her records, and finds that if she sells x cups of coffee in one day, her profit, P (in dollars) is given by  P(x) = -0.04 x^2 + 10x - 5  a. How many cups must he sell for maximum profit?  b. What is the maximum profit per day? 
  
  Solution
Solution:
a)
For P is to be maximum, dp/dx =0
=> dp/dx = d/dx(-0.04x2+10x-5) = 0
=>-0.04×2x + 10 =0
=>-0.08 x = -10
=>x = 125
So he must sell 125 cups per day for maximum profit.
b)
maximum profit per day would be :
P = -0.04(125)+ 10(125)-5
=> P =$ 1250

