the total cost (in dollars) of producing x food processors is c(x)=2500 + 30x - 0.4x^{2}. (a) find the exact…

the total cost (in dollars) of producing x food processors is c(x)=2500 + 30x - 0.4x^{2}. (a) find the exact cost of producing the 31st food processor. (b) use the marginal cost to approximate the cost of producing the 31st food processor. (a) the exact cost of producing the 31st food processor is $
Answer
Explanation:
Step1: Find cost of producing 31 processors
$C(31)=2500 + 30\times31-0.4\times31^{2}$ $C(31)=2500 + 930-0.4\times961$ $C(31)=2500 + 930 - 384.4$ $C(31)=3045.6$
Step2: Find cost of producing 30 processors
$C(30)=2500+30\times30 - 0.4\times30^{2}$ $C(30)=2500 + 900-0.4\times900$ $C(30)=2500 + 900 - 360$ $C(30)=3040$
Step3: Calculate exact cost of 31st processor
The exact cost of the 31st processor is $C(31)-C(30)$. $C(31)-C(30)=3045.6 - 3040=5.6$
Step4: Find marginal cost function
The marginal cost function $C'(x)$ is the derivative of $C(x)$. $C(x)=2500 + 30x-0.4x^{2}$, so $C'(x)=30 - 0.8x$
Step5: Approximate cost using marginal cost
Evaluate $C'(x)$ at $x = 30$. $C'(30)=30-0.8\times30$ $C'(30)=30 - 24=6$
Answer:
(A) $5.6$ (B) $6$