How many of each type of shirt must be produced and sold in order to maximize profit?
First we will find the critical point. Now,
Hence, the critical point is (2,3)
Since, D>0, and
The critical point P(2,3) has a relative maximum.
And the maximum value of profit function
The maximum profit of $19000 will be earned if 2000 shirt of $18 and 3000 shirts of $25 are produced and sold.