Answer:
(a)[tex]C'(x)=\dfrac{x^2-2560000}{x^2}[/tex]
(b)x=1600, Minimum Average Cost Per iPod=$132
(c)[tex]C''(x)=\dfrac{5120000}{x^3}[/tex]
The result, C''(1600) is positive, which means that the average cost is Concave up at the critical point, and the critical point is a minimum.
Step-by-step explanation:
Given that it costs Apple approximately $ C(x) to manufacture x 32GB iPods in a day, where:
[tex]C(x)=25,600+100x+0.01x^2[/tex]
(a)The average cost per iPod when they manufacture x iPods in a day is given by:
[tex]Cost \:Per \:iPod=\dfrac{C(x)}{x} =\dfrac{25,600+100x+0.01x^2}{x}[/tex]
The average cost per iPod is therefore:
[tex]C'(x)=\dfrac{x^2-2560000}{x^2}[/tex]
(b)To minimize average cost of x iPods per day, we set the average cost per iPod=0 and solve for x.
[tex]C'(x)=\dfrac{x^2-2560000}{x^2}=0\\x^2-2560000=0\\x^2=2560000\\x=\sqrt{2560000}=1600[/tex]
The resulting minimum average cost (at x=1600) is given as:
[tex]Cost \:Per \:iPod=\dfrac{C(x)}{x} =\dfrac{25,600+100x+0.01x^2}{x}\\\dfrac{25,600+100(1600)+0.01(1600)^2}{1600}\\=\$132[/tex]
Second derivative test
(c)The answer above is a critical point for the average cost function. To show it is a minimum, we calculate the second derivative of the average cost function.
[tex]C''(x)=\dfrac{5120000}{x^3}[/tex]
At the critical point, x=1600
[tex]C''(1600)=\dfrac{5120000}{1600^3}=0.00125[/tex]
The result, C''(1600) is positive, which means that the average cost is Concave up at the critical point, and the critical point is a minimum.