Instruction 11-6
as Part of an Evaluation Program,a Sporting Goods

Instruction 11-6
As part of an evaluation program,a sporting goods retailer wanted to compare the downhill coasting speeds of four brands of bicycles.She recorded three trials of each brand and determined their maximum downhill speeds.The results are presented in kilometres per hour in the table below.
$\begin{array}{lcccc}\text { Trial } & \frac{\text { Barth }}{} & \frac{\text { Tomado }}{} & \frac{\text { Reiser }}{} & \frac{\text { Shaw }}{} \\1 & 43 & 37 & 41 & 43 \\2 & 46 & 38 & 45 & 45 \\3 & 43 & 39 & 42 & 46\end{array}$
-Referring to Instruction 11-6,the test is valid only if the population of speeds is normally distributed.