The total cost of producing x units of a particular commodity is C(x)= 2/7x^2+65 and P(x) = 12+2x/3+x is the price at which all x units will be sold. Assume P(x) and C(x) are in dollars.

a) Find the marginal cost and marginal value

b) use marginal cost to estimate the cost of producing the fourth unit

c) find the actual cost of producing the fourth unit

d) use marginal revenue to estimate the revenue derived from the sale of the fourth unit

e) find the actual revenue derived from the sale of the fourth unit