Quiz # 8 Exponential Functions

8. A national fast food company has just analyzed the effect of the latest sales promotion. It has determined that the sales decay for its milkshakes is given by $S=420,000e^{-0.3x}$

, where $S$

 is the weekly sales and $x$

 is the number of weeks that have passes since the end of the sales promotion.

a) Determine the sales 5 weeks after the end of the promotion:  Round answer to 2 decimal places.

Sales = $ _____

b) If no new campaign is started, how many weeks after the end of the promotion will sales drop below 35,000?
Round answer to 1 decimal place.

Number of weeks _____