suppose you know σ and you want an 85% confidence level. What value would you use as z in formula of
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suppose you know σ and you want an 85% confidence level. What value would you use as z in formula of confidence interval for a population mean? (Round your answer to 2 decimal places.) |
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Value of z |
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a. |
The sample size is 15 and the level of confidence is 95%. |
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Value of t |
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b. |
The sample size is 24 and the level of confidence is 98%. |
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Value of t |
[removed] |
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c. |
The sample size is 12 and the level of confidence is 90%. |
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Value of t
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Past surveys reveal that 30% of tourists going to Las Vegas to gamble spend more than $1,000. The Visitor’s Bureau of Las Vegas wants to update this percentage. |
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a. |
The new study is to use the 90% confidence level. The estimate is to be within 1% of the population proportion. What is the necessary sample size? (Round your answer to the next whole number.) |
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Sample size |
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b. |
The Bureau feels the sample size determined above is too large. What can be done to reduce the sample? Based on your suggestion, recalculate the sample size. (Hint: Use an allowable error in the range of 0.01 to 0.05) (Round your answer to the next whole number.) |
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Sample size |
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Forty-nine items are randomly selected from a population of 500 items. The sample mean is 40 and the sample standard deviation 9. |
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Develop a 99% confidence interval for the population mean. (Round your answers to 3 decimal places.) |
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The confidence interval is between [removed] and [removed] |
