Probability and Statistics for Engineering and the Sciences (with CD-ROM and InfoTrac )

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Statistics 220, Fall 2005 Due September 7, 2005 1.10 a The stem-and-leaf plot should look something like this. 5|9 6|33588 7|00234677889 8|127 9|077 10|7 11|368 What constitutes large or small variation usually depends on the application at hand, but an often-used rule of thumb is: the variation tends to be large whenever the spread of the data (the difference between the largest and smallest observations) is large compared to a representative value. Here, “large” means that the percentage is closer to 100% than it is to 0%. For this data, the spread is 11 - 5 = 6, which constitutes 6/8 = .75, or, 75%, of the typical data value of around 8. (The median is 7.7 and the mean is 8.1.) For most applications, this is a large degree of variation. b The data isn’t particularly symmetric about any representative value. If any- thing it tends to be somewhat positively skewed — the high values go further from the peak of than the low values do. Also, the mean is higher than the median. c There aren’t any real outliers here. d There are four values > 10 — you can see this either by directly checking the data, or by counting the number of entries in the last two lines of the stem-and- leaf plot, where the stems are 10 and 11, respectively. 1
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This homework help was uploaded on 01/31/2008 for the course STAT 220 taught by Professor Shalizi during the Fall '05 term at Carnegie Mellon.

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Solutions-hw1 - Solutions to Homework Assignment#1 Statistics 220 Fall 2005 Due September 7 2005 1.10 a The stem-and-leaf plot should look

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