$11\mathrm{.}44$ Life tests of cutting tools. To improve the quality of the

$($iII$)$ output of any production process, it is necessary first to

TOOLS

understand the capabilities of the process $($Gitlow$,$ et al$.,$

Quality Management, $2017).$ In a particular manufactur$-$

ing process, the useful life of a cutting tool is related to the

speed at which the tool is operated. The data in the table

were derived from life tests for the two different brands of

cutting tools currently used in the production process. For

which brand would you feel more confident in using the

least squares line to predict useful life for a given cutting

speed? Explain.