An Introduction to Statistical Methods and Data Analysis
7th Edition
ISBN: 9781305269477
Author: R. Lyman Ott, Micheal T. Longnecker
Publisher: Cengage Learning
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Chapter 10.11, Problem 21E
Sludge is a dried product remaining from processed sewage and is often used as a fertilizer on agriculture crops. If the sludge contains a high concentration of certain heavy metals, such as nickel, the nickel may reach such a concentration in the crops that it becomes a danger to the consumer of the crops. A new method of processing sewage has been developed, and an experiment is conducted to evaluate its effectiveness in removing heavy metals. Sewage of a known concentration of nickel is treated using both the new and the old methods. One hundred tomato plants were randomly assigned to pots containing sewage sludge processed by one of the two methods. The tomatoes harvested from the plants were evaluated to determine if the nickel was at a toxic level. The results are as follows:
- a. For both treatments, place 95% confidence intervals on the proportions of plants that would have a toxic level of nickel.
- b. Is there significant evidence (α = .05) that the new treatment would produce a lower proportion of plants having a toxic level of nickel compared to the old treatment?
- c. Use the Fisher Exact test to test the research hypothesis that the new treatment would produce a lower proportion of plants having a toxic level of nickel compared to the old treatment. Compare your conclusions with the conclusions reached in part (b).
- d. Place a 95% confidence interval on the difference in the two proportions.
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Rivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the following table:
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Chapter 10 Solutions
An Introduction to Statistical Methods and Data Analysis
Ch. 10.11 - Prob. 1ECh. 10.11 - For each of the following values for and n,...Ch. 10.11 - Prob. 3ECh. 10.11 - A random sample of 1,200 units is randomly...Ch. 10.11 - A public opinion polling agency plans to conduct a...Ch. 10.11 - The test for screening donated blood for the...Ch. 10.11 - National public opinion polls are often based on...Ch. 10.11 - Prob. 17ECh. 10.11 - A large retail lawn care dealer currently provides...Ch. 10.11 - Prob. 20E
Ch. 10.11 - Sludge is a dried product remaining from processed...Ch. 10.11 - A political scientist is studying the impact of a...Ch. 10.11 - The quality control department of a motorcycle...Ch. 10.11 - Refer to Exercise 10.29. a. Place 95% confidence...Ch. 10.11 - The article “Positive Aspects of Caregiving”...Ch. 10.11 - A study examining bomb hits in South London during...Ch. 10.11 - The fire department in a large city is examining...Ch. 10.11 - Prob. 53ECh. 10.11 - A carcinogenicity study was conducted to examine...
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- Solve Exercise 14 if a 25 solution of the same mixture is added instead of pure alcohol.arrow_forwardRepeat Example 5 when microphone A receives the sound 4 seconds before microphone B.arrow_forwardRivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the following table: length weight 1616 47.0 1862 48.7 2855 55.7 1199 45.2 1320 44.7 1225 43.8 870 38.5 1455 45.8 1220 44.0 1033 40.4 Compute the correlation between length and weight for these fish. (Assume the correlation conditions have been…arrow_forward
- Rivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the following table: length weight 1616 47.0 1862 48.7 2855 55.7 1199 45.2 1320 44.7 1225 43.8 870 38.5 1455 45.8 1220 44.0 1033 40.4 Compute the correlation between length and weight for these fish. (Assume the correlation conditions have been…arrow_forwardArsenic is a naturally occurring chemical that can enter groundwater through eroding granite or from a burned forest. A health organization recommends drinking water should contain no more than 10 parts per billion (ppb) of arsenic. A company produces filters to clean arsenic from private wells that could be affected by the groundwater. The company wants to investigate the effectiveness of a new filter compared to that of an older filter. They will test the filters on a field that is bordered on one side by a granite ledge and on the other side by a burned forest. The field is divided into 88 square plots of equal size, and a well to collect groundwater is drilled in the center of each plot. One filter will be used in each well. The following diagram shows the placement of the wells in the field. The company will use four of each type of filter to conduct the investigation. A randomized block design will be used. (a) Assuming there is a difference in the effectiveness of the two…arrow_forwardThere are three types of contaminants that spoils water. Organic pollutants (0), volatile solvents (V), and chlorinated compounds (C). A new analytical method to detect (D) contaminants in water is being tested. The makers of the test claim that it can detect high levels of organic pollutants with 98% accuracy, volatile solvents with 99% accuracy, and chlorinated components with 89% accuracy. If a pollutant is not present, the test does not signal. Samples are prepared for the calibration of the test and 60% of them are contaminated with organic pollutants, 27% with volatile solvents, and 13% with traces of chlorinated compounds. A test sample is selected randomly. (a) What is the probability that the test will not signal? (b) If the test signals, what is the probability that chlorinated compounds are present? (c) If the test does not signal, what is the probability that chlorinated compounds are present? Note: Use the notations in the brackets to describe the events.arrow_forward
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