A store estimates that the total revenue (in dollars) from the sale of x bicycles per year is given by the function R(x) = 250x - .2x².

(a) Graph R(x) in the window [200, 500] by [42000, 75000].

(b) What sales level produces a revenue of $63,000?

(c) What revenue is received from the sale of 400 bicycles?

(d) Consider the situation of part (c). If the sales level were to decrease by 50 bicycles, by how much would revenue fall?

(e) The store believes that, if it spends $5000 in advertising, it can raise the total sales from 400 to 450 bicycles next year. Should it spend the $5000? Explain your conclusion.