Graphical Analysis In Exercises 21–24, you are asked to compare three data sets.
(c) Estimate the sample standard deviations. Then determine how close each of your estimates is by finding the sample standard deviations.
i.
ii.
iii.
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Graphical Analysis In Exercises 21–24, you are asked to compare three data sets.
(c) Estimate the sample standard deviations. Then determine how close each of your estimates is by finding the sample standard deviations.
i.
ii.
iii.
Shifting Data Sample annual salaries (in thousands of dollars) for employees at a company are listed.
40 35 49 53 38 39 40
37 49 34 38 43 47 35
c. Each employee in the sample takes a pay cut of \$2000 from their original salary. Find the sample mean and the sample standard deviation for the revised data set.
Use the data set and the indicated number of classes to construct
(c) a frequency polygon,
Pulse Rates
Number of classes: 6 Data set: Pulse rates of all students in a class 68 105 95 80 90 100 75 70 84 98 102 70 65 88 90 75 78 94 110 120 95 80 76 108
Mean Absolute Deviation Another useful measure of variation for a data set is the mean absolute deviation (MAD). It is calculated by the formula
MAD = Σ |x − x̄| / n.
b. Find the mean absolute deviation of the data set in Exercise 16. Compare your result with the sample standard deviation obtained in Exercise 16.
Life Spans of Tires A brand of automobile tire has a mean life span of 35,000 miles, with a standard deviation of 2250 miles. Assume the life spans of the tires have a bell-shaped distribution.
b. The life spans of three randomly selected tires are 30,500 miles, 37,250 miles, and 35,000 miles. Using the Empirical Rule, find the percentile that corresponds to each life span.
Extending Concepts
Trimmed Mean To find the 10% trimmed mean of a data set, order the data, delete the lowest 10% of the entries and the highest 10% of the entries, and find the mean of the remaining entries.
c. What is the benefit of using a trimmed mean versus using a mean found using all data entries? Explain your reasoning.