A survey of 34 college freshmen found that they average 6.46 hours of sleep each night. A 99% confidence interval had a margin of error of 0.496. a. What are the lower and upper limits of the confidence interval? b. What was the standard deviation, assuming that the population standard deviation is known? a. The lower limit of the confidence interval is and the upper limit of the confidence interval is (Round to three decimal places as needed.)

A researcher is interested in finding a 90% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 41 students who averaged 33.9 minutes concentrating on their professor during the hour lecture. The standard deviation was 11.3 minutes. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a    Correct distribution. b. With 90% confidence the population mean minutes of concentration is between ____ and ____  minutes. c. If many groups of 41 randomly selected members are studied, then a different confidence interval would be produced from each group. About ____ percent of these confidence intervals will contain the true population mean minutes of concentration and about ____ percent will not contain the true population mean minutes of concentration.

A fitness center is interested in finding a 95% confidence interval for the mean number of days per week that Americans who are members of a fitness club go to their fitness center. Records of 269 members were looked at and their mean number of visits per week was 2.2 and the standard deviation was 1.6. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a     distribution. b. With 95% confidence the population mean number of visits per week is between  and   visits. c. If many groups of 269 randomly selected members are studied, then a different confidence interval would be produced from each group. About  percent of these confidence intervals will contain the true population mean number of visits per week and about  percent will not contain the true population mean number of visits per week.

In a random sample of 50 people, the mean body mass index (BMI) was 27.7 and the standard deviation (s) was 6.12(Population standard deviation(sigma) is UNKNOWN. a. Construct a 99% confidence interval for the population mean µ.   b. Construct a 95% confidence interval for the population mean µ. Interpret the results.  c. How does decreasing the level of confidence in part (d) change the width of the confidence interval?

A researcher is interested in finding a 98% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 41 students who averaged 36.5 minutes concentrating on their professor during the hour lecture. The standard deviation was 11.6 minutes. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a    Correct distribution. b. With 98% confidence the population mean minutes of concentration is between  and   minutes. c. If many groups of 41 randomly selected members are studied, then a different confidence interval would be produced from each group. About  percent of these confidence intervals will contain the true population mean minutes of concentration and about  percent will not contain the true population mean minutes of concentration.

A researcher is interested in finding a 95% confidence interval for the mean number of times per day that college students text. The study included 112 students who averaged 26.7 texts per day. The standard deviation was 24.5 texts. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a     distribution. b. With 95% confidence the population mean number of texts per day is between  and   texts. c. If many groups of 112 randomly selected members are studied, then a different confidence interval would be produced from each group. About percent of these confidence intervals will contain the true population number of texts per day and about percent will not contain the true population mean number of texts per day.

A researcher is interested in finding a 95% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 134 students who averaged 41.1 minutes concentrating on their professor during the hour lecture. The standard deviation was 11.6 minutes. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a     distribution. b. With 95% confidence the population mean minutes of concentration is between  and   minutes. c. If many groups of 134 randomly selected members are studied, then a different confidence interval would be produced from each group. About  percent of these confidence intervals will contain the true population mean minutes of concentration and about  percent will not contain the true population mean minutes of concentration.

A researcher is interested in finding a 95% confidence interval for the mean number of times per day that college students text. The study included 137 students who averaged 42.6 texts per day. The standard deviation was 20.6 texts. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a t :v distribution. b. With 95% confidence the population mean number of texts per day is between and texts.

A researcher is interested in finding a 90% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 117 students who averaged 40.9 minutes concentrating on their professor during the hour lecture. The standard deviation was 11.8 minutes. Round answers to 3 decimal places where possible. a. To compute the confidence interval use a ? distribution. b. With 90% confidence the population mean minutes of concentration is between and minutes. c. If many groups of 117 randomly selected members are studied, then a different confidence interval would be produced from each group. About percent of these confidence intervals will contain the true population mean minutes of concentration and about percent will not contain the true population mean minutes of concentration. Submit Question

A fitness center is interested in finding a 95% confidence interval for the mean number of days per week that Americans who are members of a fitness club go to their fitness center. Records of 271 members were looked at and their mean number of visits per week was 2.3 and the standard deviation was 1.6. a. To compute the confidence interval use a ? distribution. b. With 95% confidence the population mean number of visits per week is between visits. and c. If many groups of 271 randomly selected members are studied, then a different confidence interval would be produced from each group. About percent of these confidence intervals will contain the true population mean number of visits per week and about percent will not contain the true population mean number of visits per week.