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Chapter 2: Q72E (page 110)
Question: For any set of data, what can be said about the percentage of the measurements contained in each of the following intervals?
a.xbar- sto xbar+ s
b.xbar- 2sto xbar+ 2s
c.xbar- 3sto xbar+ 3s
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Construct a relative frequency histogram for the data summarized in the accompanying table.
Answer the following questions about the variability of data sets:
a.What is the primary disadvantage of using the range to compare the variability of data sets?
b.Describe the sample variance using words rather than a formula. Do the same with the population variance.
c.Can the variance of a data set ever be negative? Explain. Can the variance ever be smaller than the standard deviation? Explain.
Refer to Exercise 2.141. Assuming all populations are approximately mound-shaped, for parts a鈥揹, determine whether the values 0, 4, and 12 are outliers.
The amount spent on textbooks for the fall term was recorded for a sample of five university students. The following data were observed: \(400, \)350, \(600, \)525, and $450. Calculate each of the following values for this data:
a.The sample mean
b.The sample median
c.The sample range
d.The standard deviation
Motivation of drug dealers.Consider a study of drug dealers and their motivation for participating in the illegal drug market (Applied Psychology in Criminal Justice, September 2009). The sample consisted of 100 convicted drug dealers who attended a court-mandated counseling program. Each dealer was scored on the Wanting Recognition (WR) Scale, which provides a quantitative measure of a person鈥檚 level of need for approval and sensitivity to social situations. (Higher scores indicate a greater need for approval.) The sample of drug dealers had a mean WR score of 39, with a standard deviation of 6. Assume the distribution of WR scores for drug dealers is mound-shaped and symmetric.
a.Give a range of WR scores that will contain about 95% of the scores in the drug dealer sample.
b.What proportion of the drug dealers had WR scores above 51?
c.Give a range of WR sores that contain nearly all the scores in the drug dealer sample.
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