### Homework #4 - Due Friday, 10/26/2007

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Please answer clearly, in full sentences, on one side only of your own paper, leaving plenty of space for remarks by the graders. Staple your pages if you can. You may collaborate with others in and out of the class, but you must prepare your own answers. Papers are due at the start of class on Friday.

A. Chapter 11:

Problem 11.4 (common stocks).
Problem 11.9 (is Popular Science like Shakespeare?)

Note: With respect to 11.4, part b: Is the "range" (largest value minus smallest value) really a good way to describe the spread? Doesn't it give more attention to the outliers than we would want? What is a better way to describe the spread?

B. Chapter 12:

Problem 12.12 (asks for a 5-number summary of the original word lengths, not the values or percentages shown in the histogram)
Problem 12.17 (mean/median)
Problem 12.18 (mean/median)
Problem 12.28 (How mean, median, and standard deviation change when the data change)

C. Chapter 13:

Problems 2, 7, 18, 24    Problem 13.2 (more mean/median)
Problem 13.7 (pregnancies)
Problem 13.18 (SAT's under 820)
Problem 13.24 (stock prices again)

Note: The last three problems are all good exercises in calculating frequencies from a normal distribution. But are they good ways to answer the questions stated? Shouldn't we demand more data, and use the actual histograms or distribution curves, instead of relying on the normal assumption? (These notes are NOT part of the homework assignment, but think about them.)

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