Chapter 3: Q9 (page 127)
Estimating s A large sample of sleep times includes values ranging from a low of 4 hours to a high of 10 hours. Use the range rule of thumb to estimate the standard deviation.
The estimated standard deviation obtained by using the range rule of thumb is 1.5 hours.
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The Empirical Rule Based on Data Set 3 “Body Temperatures” in Appendix B, body temperatures of healthy adults have a bell-shaped distribution with a mean of 98.20°F and a standard deviation of 0.62°F. Using the empirical rule, what is the approximate percentage of healthy adults with body temperatures
a. within 1 standard deviation of the mean, or between 97.58°F and 98.82°F?
b. between 96.34°F and 100.06°F?
Boxplot Comparison Refer to the boxplots shown below that are drawn on the same scale. One boxplot represents weights of men, and the other boxplot represents weights of women. Which boxplot represents weights of women? Explain.
Mean Absolute Deviation Use the same population of {9 cigarettes, 10 cigarettes, 20 cigarettes} from Exercise 45. Show that when samples of size 2 are randomly selected with replacement, the samples have mean absolute deviations that do not centre about the value of the mean absolute deviation of the population. What does this indicate about a sample mean absolute deviation being used as an estimator of the mean absolute deviation of a population?
In Exercises 21–24, find the mean and median for each of the two samples, then compare
the two sets of results.
Pulse Rates Listed below are pulse rates (beats per minute) from samples of adult males and females (from Data Set 1 “Body Data”in Appendix B). Does there appear to be a difference?
Male: 86 72 64 72 72 54 66 56 80 72 64 64 96 58 66
Female: 64 84 82 70 74 86 90 88 90 90 94 68 90 82 80
Weighted Mean A student of the author earned grades of A, C, B, A, and D. Those courses had these corresponding numbers of credit hours: 3, 3, 3, 4, and 1. The grading system assigns quality points to letter grades as follows: A = 4; B = 3; C = 2; D = 1; F = 0. Compute the grade-point average (GPA) and round the result with two decimal places. If the dean’s list requires a GPA of 3.00 or greater, did this student make the dean’s list?
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