91影视

Which Method? Refer to Exercise 7 鈥淩equirements鈥� and assume that sample of 12 voltage levels appears to be from a population with a distribution that is substantially far from being normal. Should a 95% confidence interval estimate ofbe constructed using the ${蠂}^2$distribution? If not, what other method could be used to find a 95% confidence interval estimate of$蟽$.

Formats of Confidence Intervals. In Exercises 9鈥�12, express the confidence interval using the indicated format. (The confidence intervals are based on the proportions of red, orange, yellow, and blue M&Ms in Data Set 27 鈥淢&M Weights鈥� in Appendix B.)

Yellow M&Ms Express the confidence interval (0.0169, 0.143) in the form of$\hat{p}-E<p<\hat{p}+E$

Mean Body Temperature Data Set 3 鈥淏ody Temperatures鈥� in Appendix B includes a sample of 106 body temperatures having a mean of 98.20掳F and a standard deviation of 0.62掳F. Construct a 95% confidence interval estimate of the mean body temperature for the entire population. What does the result suggest about the common belief that 98.6掳F is the mean body temperature?

In Exercises 9鈥�16, assume that each sample is a simplerandom sample obtained from a population with a normal distribution.

Insomnia Treatment A clinical trial was conducted to test the effectiveness of the drug zopiclone for treating insomnia in older subjects. After treatment with zopiclone, 16 subjects had a mean wake time of 98.9 min and a standard deviation of 42.3 min (based on data from 鈥淐ognitive Behavioral Therapy vs Zopiclone for Treatment of Chronic Primary Insomnia in Older Adults,鈥� by Sivertsen et al.,Journal of the American Medical Association,Vol. 295, No. 24). Assume that the 16 sample values appear to be from a normally distributed population and construct a 98% confidence interval estimate of the standard deviation of the wake timesfor a population with zopiclone treatments. Does the result indicate whether the treatment is effective?

Formats of Confidence Intervals. In Exercises 9鈥�12, express the confidence interval using the indicated format. (The confidence intervals are based on the proportions of red, orange, yellow, and blue M&Ms in Data Set 27 鈥淢&M Weights鈥� in Appendix B.)

Blue M&Ms Express the confidence interval 0.270$卤$0.073 in the form of$\hat{p}-E<p<\hat{p}+E$

In Exercises 9鈥�16, assume that each sample is a simplerandom sample obtained from a population with a normal distribution.

Garlic for Reducing Cholesterol In a test of the effectiveness of garlic for lowering cholesterol, 49 subjects were treated with raw garlic. Cholesterol levels were measured before and after the treatment. The changes (before minus after) in their levels of LDL cholesterol(in mg/dL) had a mean of 0.4 and a standard deviation of 21.0 (based on data from 鈥淓ffect of Raw Garlic vs Commercial Garlic Supplements on Plasma Lipid Concentrations in Adults with Moderate Hypercholesterolemia,鈥� by Gardner et al.,Archives of Internal Medicine,Vol. 167).Construct a 98% confidence interval estimate of the standard deviation of the changes in LDL cholesterol after the garlic treatment. Does the result indicate whether the treatment is effective?

Atkins Weight Loss Program In a test of weight loss programs, 40 adults used the Atkins weight loss program. After 12 months, their mean weight loss was found to be 2.1 lb, with a standard deviation of 4.8 lb. Construct a 90% confidence interval estimate of the mean weight loss for all such subjects. Does the Atkins program appear to be effective? Does it appear to be practical?

In Exercises 9鈥�16, assume that each sample is a simple random sample obtained from a population with a normal distribution.

Speed Dating In a study of speed dating conducted at Columbia University, male subjects were asked to rate the attractiveness of their female dates, and a sample of the results is listed below (1 = not attractive; 10 = extremely attractive). Construct a 95% confidence interval estimate of the standard deviation of the population from which the sample was obtained.

7 8 2 10 6 5 7 8 8 9 5 9

Constructing and Interpreting Confidence Intervals. In Exercises 13鈥�16, use the given sample data and confidence level. In each case, (a) find the best point estimate of the population proportion p; (b) identify the value of the margin of error E; (c) construct the confidence interval; (d) write a statement that correctly interprets the confidence interval.

In a study of the accuracy of fast food drive-through orders, McDonald鈥檚 had 33 orders that were not accurate among 362 orders observed (based on data from QSR magazine).

Construct a 95% confidence interval for the proportion of orders that are not accurate.

Insomnia Treatment A clinical trial was conducted to test the effectiveness of the drug zopiclone for treating insomnia in older subjects. Before treatment with zopiclone, 16 subjects had a mean wake time of 102.8 min. After treatment with zopiclone, the 16 subjects had a mean wake time of 98.9 min and a standard deviation of 42.3 min (based on data from 鈥淐ognitive Behavioral Therapy vs Zopiclone for Treatment of Chronic Primary Insomnia in Older Adults,鈥� by Sivertsen et al., Journal of the American Medical Association, Vol. 295, No. 24). Assume that the 16 sample values appear to be from a normally distributed population and construct a 98% confidence interval estimate of the mean wake time for a population with zopiclone treatments. What does the result suggest about the mean wake time of 102.8 min before the treatment? Does zopiclone appear to be effective?