1.You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=56.3σ=56.3. You would like to be 99% confident that your esimate is within 2.5 of the true population mean. How large of a sample size is required?n = 2. A smart phone manufacturer is interested in constructing a 95% confidence interval for the proportion of smart phones that break before the warranty expires. 80 of the 1686 randomly selected smart phones broke before the warranty expired. Round answers to 4 decimal places where possible. a. With 95% confidence the proportion of all smart phones that break before the warranty expires is between and . b. If many groups of 1686 randomly selected smart phones are selected, then a different confidence interval would be produced for each group. About percent of these confidence intervals will contain the true population proportion of all smart phones that break before the warranty expires and about percent will not contain the true population proportion.
1.You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=56.3σ=56.3. You would like to be 99% confident that your esimate is within 2.5 of the true population mean. How large of a sample size is required?
n =
2. A smart phone manufacturer is interested in constructing a 95% confidence interval for the proportion of smart phones that break before the warranty expires. 80 of the 1686 randomly selected smart phones broke before the warranty expired. Round answers to 4 decimal places where possible.
a. With 95% confidence the proportion of all smart phones that break before the warranty expires is between and .
b. If many groups of 1686 randomly selected smart phones are selected, then a different confidence interval would be produced for each group. About percent of these confidence intervals will contain the true population proportion of all smart phones that break before the warranty expires and about percent will not contain the true population proportion.
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