Answer:
a) Marginal cost = 2400 - 0.08x
At x = 4, marginal cost = $2399.68 thousand dollars
The cost is going up at the rate of **$ (2400 - 0.08 (x))** per television commercial. The exact cost of airing the fifth commercial is **$2399.64 thousand dollars**. Thus, there is a difference of **$0.04 thousand dollars**.
b) Average cost function = (150/x) + 2400 - 0.04x
At x = 4, C(4) = 2,437.34
The average cost of airing the first four commercials is **$2437.34 thousand dollars** per commercial.
Step-by-step explanation:
C(x) = 150 + 2400x − 0.04x²
Marginal cost = C'(x) = dC/dx = 2400 - 0.08x
At x = 4,
C'(x) = 2400 - 0.08(4) = 2399.68
The rate of increase is obviously [2400 - 0.08(x)]
The exact cost of airing the 5th commercial
C(5) - C(4)
= [150 + 2400(5) - 0.04(5²)] - [150 + 2400(4) - 0.04(4²) = 12149 - 9749.36 = $ 2399.64 thousand dollars
C'(5) = 2400 - 0.08(5) = 2399.6 thousand dollars.
b) Average cost = Total cost/quantity = [C(x)]/x= (150 + 2400x − 0.04x²)/x = (150/x) + 2400 - 0.04x
At x = 4, C(4) =
Average cost function = (150/4) + 2400 - 0.04(4) = $2,437.34 thousand dollars.