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Chapter 3: Q3 (page 107)
Variance The 20 subjects used in Data Set 8 鈥淚Q and Brain Size鈥� in Appendix B have weights with a standard deviation of 20.0414 kg. What is the variance of their weights? Be sure to include the appropriate units with the result.
The variance of the weights of the 20 twins is equal to 401.6577.
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In Exercises 21鈥�24, find the coefficient of variation for each of the two samples; then compare the variation. (The same data were used in Section 3-1.) 21.
Bank Queues Waiting times (in seconds) of customers at the Madison Savings Bank are recorded with two configurations: single customer line; individual customer lines.
Single Line 390 396 402 408 426 438 444 462 462 462
Individual Lines 252 324 348 372 402 462 462 510 558 600
In Exercises 5鈥�20, find the range, variance, and standard deviation for the given sample data. Include appropriate units (such as 鈥渕inutes鈥�) in your results. (The same data were used in Section 3-1, where we found measures of center. Here we find measures of variation.) Then answer the given questions.
Fireighter Fatalities Listed below are the numbers of heroic firefighters who lost their lives in the United States each year while fighting forest fires. The numbers are listed in order by year, starting with the year 2000. What important feature of the data is not revealed by any of the measures of variation?
20 18 23 30 20 12 24 9 25 15 8 11 15 34
In Exercises 5鈥�20, find the range, variance, and standard deviation for the given sample data. Include appropriate units (such as 鈥渕inutes鈥�) in your results. (The same data were used in Section 3-1, where we found measures of center. Here we find measures of variation.) Then answer the given questions.
California Smokers In the California Health Interview Survey, randomly selected adults are interviewed. One of the questions asks how many cigarettes are smoked per day, and results are listed below for 50 randomly selected respondents. How well do the results reflect the smoking behavior of California adults?
9 10 10 20 40 50 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
In Exercises 21鈥�28, use the same list of Sprint airport data speeds (Mbps) given for Exercises 17鈥�20. Find the indicated percentile or quartile.
P40
In Exercises 21鈥�28, use the same list of Sprint airport data speeds (Mbps) given for Exercises 17鈥�20. Find the indicated percentile or quartile.
Q1
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