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Compute without a calculator 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.


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

    An example combination histogram and boxplot has been provided.

    A combined histogram, and box plot,  x axis scaled in equal segments by 5, from 250 to 295. Histogram, starting at the left, each segment has the following bar heights: 6, 4, 2, 1, 1, 0, 0, 0, 1. Box plot: Left whisker: 250 to 253, Box: 253 to 263, with vertical line at 257, Right whisker: 263 to 270, with outlier at 291.

  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 . The histogram is single-peaked and skewed.
    The data is concentrated in the 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?

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