### Home > CCA > Chapter 11 > Lesson 11.2.2 > Problem11-46

11-46.

The auto repair shop is concerned about the reliability of its brake lathe. A lathe 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:

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.

2. Describe center, shape, spread, and outliers, similar to the way you did in problem 11-34.

Where is the center?
How many peaks are there?
Is the histogram symmetric or skewed?
What is the IQR?
Are there any outliers?

The center is at about 257-260. The histogram is single-peaked and skewed.
The IQR is 10 RPM. There is one outlier, 291.

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

Calculate the mean. Is the mean or the median a better description of the center?

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