Let 10p + x = 100 be the demand equation, where p is the price per item when x items are demanded.
(a) Find the total revenue when the level of production is:
(i) 40;
(ii) 41;
(b) Find the exact revenue derived from the 41st item.
(c) Find the approximate revenue derived from the 41st item.
(d) What is the error if the derivative is used to approximate the marginal revenue?