Applications Of Derivatives Question 60

Question: The profit function, in rupees, of a firm selling x items $ (x\ge 0) $ per week is given by $ P(x)=-3500+(400-x)x $ . How many items should the firm sell so that the firm has maximum profit-

Options:

A) 400

B) 300

C) 200

D) 100

Show Answer

Answer:

Correct Answer: C

Solution:

[c] $ P(x)=-3500+(400-x)x= $ $ -3500+400x-x^{2} $

On differentiating w.r.t.x, we get $ P’(x)=400-2x $ Put $ P’(x)=0 $

for maxima or minima
$ \Rightarrow 400-2x=0 $

$ \Rightarrow x=200 $ Now $ P’’(x)=-2x $

$ \Rightarrow P’’(200)=-400<0 $

$ \therefore ,P(x) $ is maximum at $ x=200 $

Hence 200 items should the firm sell so that the firm has maximum profit.