# Describing Data Visually

Topics: Skewness, Inequality, Rounding Pages: 4 (455 words) Published: February 21, 2012
Chapter 3

Describing Data Visually

3.1
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Approximately symmetric, but can be viewed as skewed to the left.

3.2

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Range 91 to 204 with some clustering near 130; distribution appears very slightly skewed right.

3.3
Sarah’s Calls:

[pic]

Bob’s Calls:

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Sarah’s makes more calls than Bob and her calls are shorter in duration.

3.4a. 7 bins of 20

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b. Answers will vary. Too few bins (less than five) or too many bins (more than 15) might hide the skewness in the distribution.

3.5a. 6 bins of 100
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b. Answers will vary. Too few bins (less than five) or too many bins (more than 15) might hide the skewness in the distribution.

3.6a. 4 bins of 10

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b. Answers will vary. Too few bins (less than five) or too many bins (more than 15) might hide the skewness in the distribution.

3. 7a. Suggest 7 bins with width 5. Sturges’ Rule shows the number of bins to be 7 with bin width (38.7-9.4)/7 = 4.19 so rounding up, 5. Yes, Sturges’ rule does agree. b. Suggest 7 bins with width 10. Sturges’ Rule shows the number of bins to be 7 with bin width (85-12)/7 = 10.43 so 10. Yes, Sturges’ rule does agree.

c. Suggest 8 bins with width .20. Sturges’ Rule shows the number of bins to be 9 with bin width (3.71-2.25)/9 = 0.162 so rounding up, .20 (requiring only 8 bins). Yes, Sturges’ rule does agree. d. Suggest 8 bins with width .01. Sturges’ Rule shows the number of bins to be 8 with bin width (.097-.023)/8 = .00925 so rounding up, .01. Yes, Sturges’ rule does agree.

3.8
a.
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