The Following Data Present the Number of Computer Units Sold

Short Answer

The following data present the number of computer units sold per day by a sample of 6 salespersons before and after a bonus plan was implemented.
$\begin{array}{lll}\text { sales person }&\text { Before }&\text { After }\\1 & 3 & 6 \\2 & 7 & 5 \\3 & 6 & 6 \\4 & 8 & 7 \\5 & 7 & 8 \\6 & 9 & 8\end{array}$ At 95% confidence, test to see if the bonus plan was effective. That is, did the bonus plan actually increase sales? Let d = Before - After.