a. Given that, R(x)=0.006x^3+0.04x^2+0.4x, to find the value of current revenue, we substitute 60(current quantity of production) into x in the equation.Therefore,

current revenue = 0.006(60^3)+0.04(60^2)+0.4(60) =1464

b. R(64) is the value of revenue when production(x) is 64 units

R(64) = 0.006(64^3)+0.04(64^2)+0.4(64) = 1762.30

To get the value by which revenue increases, we subtract the amunt of evenue at x=60 from the amount of revenue at x=64. Hence,

Revenue increases by R(64)-R(60) = 1762.3-1464 =298.30

c. Marginal revenue function(MR) is the derivative of the total revenue function

hence to derive the marginal revenue function,we differentiate the total revenue function R(x)

MR(x) = R'(x)

MR(X) =0.018X^2+0.08X+0.4

Substituting the value of x(60) into the MR(x) gives,