Statistics for Engineers and Scientists - With Access
4th Edition
ISBN: 9781259275975
Author: Navidi
Publisher: MCG
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Textbook Question
Chapter 5.2, Problem 7E
Refer to Exercise 2. Find a 98% upper confidence bound for the proportion of residences that reduced their water consumption.
2. During a recent drought, a water utility in a certain town sampled 100 residential water bills and found that 73 of the residences had reduced their water consumption over that of the previous year.
- a. Find a 95% confidence interval for the proportion of residences that reduced their water consumption.
- b. Find a 99% confidence interval for the proportion of residences that reduced their water consumption.
- c. Find the sample size needed for a 95% confidence interval to specify the proportion to within ±0.05.
- d. Find the sample size needed for a 99% confidence interval to specify the proportion to within ±0.05.
- e. Someone claims that more than 70% of residences reduced their water consumption. With what level of confidence can this statement be made?
- f. If 95% confidence intervals are computed for 200 towns, what is the probability that more than 192 of the confidence intervals cover the true proportions?
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Chapter 5 Solutions
Statistics for Engineers and Scientists - With Access
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