Effect of Advertising on Sales Metro Department Store found that t weeks after the end of a sales promotion the volume of sales was given by S(t) = B + Ae-kt (0 s t s 4) where B = 41,000 and is equal to the average weekly volume of sales before the promotion. The sales volumes at the end of the first and third weeks were $84,540 and $64,220, respectively. Assume that the sales volume is decreasing exponentially. (a) Find the decay constant k. (Round your answer to five decimal places.) k = (b) Find the sales volume at the end of the fourth week. (Round your answer to the nearest whole number.) $