2. A simple random sample of 35 observations is derived from a normally distributed population with a known standard deviation of 6.3. [You may find it useful to reference the z table.] c. Compute the margin of error with 90% confidence. (Round intermediate calculations to at least 4 decimal places. Round "z" value to 3 decimal places and final answer to 2 decimal places.) 3. In order to estimate the mean 30-year fixed mortgage rate for a home loan in the United States, a random sample of 26 recent loans is taken. The average calculated from this sample is 7.20%. It can be assumed that 30-year fixed mortgage rates are normally distributed with a standard deviation of 0.7%. Compute 95% and 99% confidence intervals for the population mean 30-year fixed mortgage rate. (You may find it useful to reference the z table. Round intermediate calculations to at least 4 decimal places. Round "z" value to 3 decimal places and final answers to 2 decimal places. Enter your answers as percentages, not decimals.) 4. An article in the National Geographic News (“U.S. Racking Up Huge Sleep Debt,” February 24, 2005) argues that Americans are increasingly skimping on their sleep. A researcher in a small Midwestern town wants to estimate the mean weekday sleep time of its adult residents. He takes a random sample of 80 adult residents and records their weekday mean sleep time as 6.4 hours. Assume that the population standard deviation is fairly stable at 1.8 hours. [You may find it useful to reference the z table.]a. Calculate the 95% confidence interval for the population mean weekday sleep time of all adult residents of this Midwestern town. (Round intermediate calculations to at least 4 decimal places. Round "z" value to 2 decimal places and final answers to 2 decimal places.)
2. A simple random sample of 35 observations is derived from a
c. Compute the margin of error with 90% confidence. (Round intermediate calculations to at least 4 decimal places. Round "z" value to 3 decimal places and final answer to 2 decimal places.)
3. In order to estimate the mean 30-year fixed mortgage rate for a home loan in the United States, a random sample of 26 recent loans is taken. The average calculated from this sample is 7.20%. It can be assumed that 30-year fixed mortgage rates are normally distributed with a standard deviation of 0.7%. Compute 95% and 99% confidence intervals for the population mean 30-year fixed mortgage rate. (You may find it useful to reference the z table. Round intermediate calculations to at least 4 decimal places. Round "z" value to 3 decimal places and final answers to 2 decimal places. Enter your answers as percentages, not decimals.)
4. An article in the National Geographic News (“U.S. Racking Up Huge Sleep Debt,” February 24, 2005) argues that Americans are increasingly skimping on their sleep. A researcher in a small Midwestern town wants to estimate the mean weekday sleep time of its adult residents. He takes a random sample of 80 adult residents and records their weekday mean sleep time as 6.4 hours. Assume that the population standard deviation is fairly stable at 1.8 hours. [You may find it useful to reference the z table.]
a. Calculate the 95% confidence interval for the population mean weekday sleep time of all adult residents of this Midwestern town. (Round intermediate calculations to at least 4 decimal places. Round "z" value to 2 decimal places and final answers to 2 decimal places.)
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