You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately o = 61.8. You would like to be 99% confident that your estimate is within 5 of the true population mean. How large of a sample size is required? Hint: Video B [+] n =

We want to obtain a sample to estimate a population mean. Based on previous evidence, researchers believe the population standard deviation is approximately o = 22.4. We would like to be 98% confident that the estimate is within 4 of the true population mean. How large of a sample size is required? %3D Hint: Did you round up to the nearest whole number? Question Help: M Message instructor

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 124 students who averaged 33.8 minutes concentrating on their professor during the hour lecture. The standard deviation was 12.6 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 124 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.

The amount of trash generated by US households (in lbs per day) is normally distributed. You take a sample of 10 people. The sample average is xbar=10.91 lbs, and the sample standard deviation is s=4.736. What is the 99% Conf. Int. for the mean?   Group of answer choices a. 6.04 to 15.78 b. 8.33 to 13.49 c. 8.09 to 13.73 d. 7.74 to 14.08