(a) If $C ( x )$ is the cost of producing $x$ units of a commodity,
then the average cost per unit is $c ( x ) = C ( x ) / x$ . Show
that if the average cost is a minimum, then the marginal
cost equals the average cost.
(b) If $C ( x ) = 16,000 + 200 x + 4 x ^ { 3 / 2 } ,$ in dollars, find $( \mathrm { i } )$ the
cost, average cost, and marginal cost at a production
level of 1000 units; (ii) the production level that will
minimize the average cost; and (iii) the minimum aver-
age cost.