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C-26.

The auto repair shop is concerned about the reliability of its brake lathe, which is a rotating piece of equipment used in restoring parts. The shop’s owner measured the speed (in rotations per minute) at various times over the course of a month. These were his measurements: C-26 HW eTool.

$250, 251, 253, 253, 253, 254, 257, 257, 259, 259, 261, 263, 265, 270, 291$ RPM

1. On grid paper, draw a combination histogram and boxplot. Do not use a calculator.

An example combination histogram and boxplot has been provided.

2. Describe center, shape, spread, and outliers, similar to the way you did in problem C-11.

Where is the center? Are most of the points concentrated there? How many peaks are there? Are there equal amounts of points on either side of the peak? Are there any places where the data is much more concentrated than anywhere else? Are there any points far from all of the others?

The center is at about $257-260$. The histogram is single-peaked and skewed.
The data is concentrated in the $250-260$ range. What else can you say about the graph?

3. When reporting the center of this data, or the “typical RPM,” which would be more appropriate, the mean or the median? Why?

Find the median and the average. Which one seems closer to the majority of the data points? Is there anything that could change the mean or median and make it a less accurate representation, such as an outlier?

Explore using the eTool below.
Click the link to the right for full version. CCA2 C-26 HW eTool.