EFFECT OF ADVERTISING ON Sales Metro Department Store found that i weeks after the end of a sales promotion the volume of sales was given by S(t) = B + Ae-ke ( 014) where B = 50,000 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 $83,515 and $65,055, respectively. Assume that the sales volume is decreasing exponentially a. Find the decay constant k. b. Find the sales volume at the end of the fourth week.