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Sample size determination

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16. A study of 305 computer chips found that 244 chips functioned properly. Develop a 99 percent confidence interval for the population proportion of properly functioning computer chips.
17. A correctional institution would like to report the mean amount of money spent per day on operating the facilities. How many days should be considered if a 95 percent confidence is used and the estimate is to be within one hundred dollars? The standard deviation is $400.

18. The Corporate Lawyer, a magazine for corporate lawyers, would like to report the mean amount earned by lawyers in their area of specialization. How large a sample is required if the 97 percent level of confidence is used and the estimate is to be within $2,500? The standard deviation is $16,000.

19. The Customer Relations Department at Commuter Airline, Inc. wants to estimate the proportion of customers that carry only hand luggage. The estimate is to be within 0.03 of the true proportion with 95 percent level of confidence. No estimate of the population proportion is available. How large a sample is required?

20. A survey is being conducted on a local mayoral election. If the poll is to have a 98 percent confidence interval and must be within four percentage points, how many people should be surveyed?

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Solution Summary

Step by step method for the construction of confidence interval and sample size are given in the solution

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Sample size

In Yahoo! use the search term "Sample Size Determination." Select a University or Government webpage that discusses the topic.

Paragraph 1: In simple terms explain what researchers must go through to select the right sample size for a study. (Be sure to cite and reference the website)

Paragraph 2: Explain how the calculators work. Test the two calculators using a population, confidence level and confidence interval you select. Discuss the results. (Be sure to cite and reference the website)

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