Answer:
The production would be 25 wheels,
Lowest average cost is $ 123.75
Step-by-step explanation:
Given cost function,

Where,
x = number of wheel,
So, the average cost per wheel,

Differentiating with respect to x,

Again differentiating with respect to x,

For maxima or minima,




For x = 25, A''(x) = positive,
i.e. A(x) is maximum at x = 25.
Hence, the production would be 25 wheels for the lowest average cost per wheel.
And, lowest average cost,
A(x) = 0.09(25)² - 4.5(25) + 180 = $ 123.75