In: Math
The monthly sales of Stewart Electronics' new sound system are given by q(t) = 2000t - 100t2 units per month, t months after its introduction. The price Stewart charges is p(t) = 1000 - t2 dollars per sound system, t months after introduction.
a. Find the rate of change of monthly sales after 6 months.
b. Find the rate of change of monthly price after 6 months.
c. Find the equation of the rate of change of the monthly revenue.
d. Find the rate of change of the monthly revenue after 6 months.
Answer :
The monthly sales of Stewart Electronics' new sound system are given by q(t) = 2000t - 100t2 units per month, t months after its introduction.
The price Stewart charges is p(t) = 1000 - t2 dollars per sound system, t months after introduction.
(a) Then q'(t) = 2000 - 200t
when t = 6 we have q'(6) = 2000 - 200(6) = 800
The rate of change of monthly sales after 6 months is 800 dollars /month.
(b) And now p'(t) = - 2t
when t = 6 we have p'(6) = - 2(6) = - 12
The rate of change of monthly price after 6 months is - 12 dollars/month.
(c) The revenue is given by R(t) = tp(t) - q(t)
R(t) = 1000t - t3 - ( 2000t - 100t2 ) = - t3 - 1000t + 100t2
The equation of the rate of change of the monthly revenue is R'(t) = - 3t2 - 1000 + 200t
(d) when t = 6 we have R'(6) = -3(62) - 1000 + 200(6) = 92
The rate of change of the monthly revenue after 6 months is 92 dollars per month