Chapter 2: Q73E (page 110)
Question: For a set of data with a mound-shaped relative frequency distribution, what can be said about the percentage of the measurements contained in each of the intervals specified in Exercise 2.72?
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Permeability of sandstone during weathering.Refer to the Geographical Analysis(Vol. 42, 2010) study of the decay properties of sandstone when exposed to the weather, Exercises 2.47 and 2.65 (pp. 96 and 104). Recall that slices of sandstone blocks were measured for permeability under three conditions: no exposure to any type of weathering (A), repeatedly sprayed with a 10% salt solution (B), and soaked in a 10% salt solution and dried (C).
a.Combine the mean (from Exercise 2.47) and standard deviation (from Exercise 2.65) to make a statement about where most of the permeability measurements for Group A sandstone slices will fall. Which rule did you use to make this inference and why?
b.Repeat part afor Group B sandstone slices.
c.Repeat part afor Group C sandstone slices.
d.Based on all your analyses, which type of weathering (type A, B, or C) appears to result in faster decay (i.e., higher permeability measurements)?
Construct a scattergram for the data in the following table.
Variable 1: 174 268 345 119 400 520 190 448 307 252 Variable 2: 8 10 15 7 22 31 15 20 11 9 |
Lead in drinking water. The U.S. Environmental Protection Agency (EPA) sets a limit on the amount of lead permitted in drinking water. The EPA Action Level for lead is .015 milligram per liter (mg/L) of water. Under EPA guidelines, if 90% of a water system’s study samples have a lead concentration less than .015 mg/L, the water is considered safe for drinking. I (coauthor Sincich) received a recent report on a study of lead levels in the drinking water of homes in my subdivision. The 90th percentile of the study sample had a lead concentration of .00372 mg/L. Are water customers in my subdivision at risk of drinking water with unhealthy lead levels? Explain.
Question: The output from a statistical software package indicates that the mean and standard deviation of a data set consisting of 200 measurements are \(1,500 and \)300, respectively.
a.What are the units of measurement of the variable of interest? Based on the units, what type of data is this: quantitative or qualitative?
b.What can be said about the number of measurements between \(900 and \)2,100? Between \(600 and \)2,400? Between \(1,200 and \)1,800? Between \(1,500 and \)2,100?
Question: Hotels’ use of ecolabels.Refer to the Journal of Vacation Marketing(January 2016) study of travelers’ familiaritywith ecolabels used by hotels, Exercise 2.42 (p. 94). Recallthat a sample of 392 adult travelers were shown a list of6 different ecolabels, and asked, “How familiar are youwith this ecolabel, on a scale of 1 (not familiar at all) to5 (very familiar).” The mean and standard deviation ofthe responses for each ecolabel are provided in the table.Which of the ecolabels had the most variation in numericalresponses? Explain.
Ecolabel | Mean | Std. Dev. |
Energy Star | 4.44 | 0.82 |
TripAdvisor | 3.57 | 1.38 |
Green Leaders Audubon | 2.41 | 1.44 |
International U.S Green | 2.28 | 1.39 |
Building Council Green Business | 2.25 | 1.39 |
Green Key | 2.01 | 1.30 |
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