AC(x) = 30,000 +3x / X gives the average per unit cost, in dollars, for producing a small calculator. As the number of calculators produced gets very...

AC(x) =  30,000 +3x / X gives the average per unit cost, in dollars, for producing a small calculator. As the number of calculators produced gets very large, the average per unit cost will approach:

Select one:

A. $30,000/x

B. $3/x

C. $3x

D. $3

E. Can't be determined from the info given.

The weekly profit of a custom surfboard manufacturer, in dollars, is given by the quadratic function:  P(x) = -4x2 + 400x- 3600.  Find the number of boards that will maximize weekly profit, and find the maximum weekly profit.

Select one:

A. 30 boards ; $4800 profit

B. 40 boards ; $6000 profit

C. 50 boards ; $6400 profit

D. 50 boards ; $26400 profit

E. None of the above.