Automotive Parts
a Regional Automotive Parts Chain Store Firm Wants

Automotive parts
A regional automotive parts chain store firm wants to improve the sales of tune-up supplies.It believes that a TV ad with a popular local,but offbeat,know-it-all actor might be able to affect their sales.Before the ads are run on TV,the company randomly samples eight of its weekly sales from past years.Following the ad campaign,eight weeks of sales were sampled.Weekly sales are approximately normally distributed and the population standard deviations are equal.Their hypothesis test is: Did the TV ad campaign help or hurt sales? To answer this question,the company plans to use a 0.05 significance level.The results of the two samples are: $$\begin{array} { | c | c | } \hline \text { Before Ad Campaign } & \text { After Ad Campaign } \\\hline n _ { 1 } = 8 & n _ { 2 } = 8 \\\bar { x } _ { 1 } = 184 & \bar { x } _ { 2 } = 189 \\s _ { 1 } ^ { 2 } = 548 & s _ { 2 } ^ { 2 } = 456 \\\hline\end{array}$$
-What is the test statistic?
Appropriate test: ____________________
Test statistic = ____________________