LetC(q) represent the cost,R(q) the revenue, and(q) the total profit, in dollars, of producingqitems.

(a)

IfC'(50) =70

andR'(50) =86,

approximately how much profit (in dollars) is earned by the 51st item?

(b)

IfC'(90) =79

andR'(90) =61,

approximately how much profit (in dollars) is earned by the 91st item?

(c)

If(q) is a maximum whenq= 78,

how do you thinkC'(78) andR'(78) compare?

C'(78) is what to R'(78)