Homework for Section 1.2  means, standard deviations
1. For each data set,
make a histogram
find
f8e5
X and s
mark the positions of
f8e5
X and
f8e5
X ± s on the histogram.
a. 1, 3, 3, 3, 5
b. 1, 1, 3, 5, 5
c. 1, 1, 1, 2, 5
d. 1, 1, 1, 2, 20
(For this data,
f8e5
X
!
s will be a negative number.)
2. For which of the data sets in question 1 are the mean and standard deviations good
measures of the center and spread?
3. A misleading graphic in the textbook:
Look at the data summarized in the example at the top of page 44.
The data is
for the returns of two kinds of investments: common stocks and treasury bills.
Which
kind of investment has the larger standard deviation?
Now look at the stemplots for the same data at the bottom of the page.
Plot a is
for stocks and plot b is for treasury bills.
Which investment looks like it has a bigger
standard deviation in the stemplots?
How did they make it look that way?
4.
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 Spring '08
 Staff
 Statistics, Probability, Standard Deviation, Mean

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