Homework $($cont$\text{'}$d$)$

$4.$ The tapedata.xlsx file contains data for weeks during $2009-2011$ for the unit sales of $3M$ tape, price charged, whether an ad campaign was run that week $(1=$ ad campaign$),$ and whether the product was displayed on the end of the aisle end cap$).$ Use this file to perform the following exercises:

a$.$ Does there appear to be an upward trend in sales?

b$.$ Analyze the nature of the monthly seasonality of tape sales.

c$.$ Does an ad campaign appear to increase sales?

d$.$ Does placing the tape in an end$-$cap display appear to increase sales?