Final answer:
To find the revenue earned from selling 85 fountains, substitute x=85 in R(x). The marginal revenue function is the derivative of R(x). The marginal revenue when 85 fountains are sold can be found by substituting x=85 in MR(x). To estimate the revenue from selling 86 fountains, substitute x=86 in R(x).
Step-by-step explanation:
a) To find the revenue earned from selling 85 fountains, we can substitute x=85 in the revenue function R(x)=0.62x^3−7.4x^2+2510x. Evaluating the expression, we get R(85) = 0.62(85)^3 - 7.4(85)^2 + 2510(85).
b) The marginal revenue function can be found by taking the derivative of the revenue function with respect to x. So, the marginal revenue function is given by MR(x) = 3(0.62x^2) - 2(7.4x) + 2510.
c) The marginal revenue when 85 fountains are sold can be found by substituting x=85 in the marginal revenue function MR(x) = 3(0.62x^2) - 2(7.4x) + 2510.
d) We can estimate the revenue that would result in selling 86 fountains by substituting x=86 in the revenue function R(x)=0.62x^3−7.4x^2+2510x. Evaluating the expression, we get R(86) = 0.62(86)^3 - 7.4(86)^2 + 2510(86).