Effect of advertising on sales the relationship between the

Question

Question: EFFECT OF ADVERTISING ON SALES The relationship between the amount of money x that Cannon Precision Instruments spends on advertising and the company's total sales S(x) is given by the function

S(x) = -0.002x³ + 0.6x² + x + 500       (0 ≤ x ≤ 200)

where x is measured in thousands of dollars. Find the rate of change of the sales with respect to the amount of money spent on advertising. Are Cannon's total sales increasing at a faster rate when the amount of money spent on advertising is

(a) $100,000 or

(b) $150,000?