The mean replacement time for a random sample of 12 microwave ovens is 8.6 years with a standard deviation of 3.6 years. Construct a 95% confidence interval for the population standard deviation.

A labor department wants to study mean age of all people in the civilian labor force. The average age of 49 randomly selected people in the civilian labor force is found to be 35.6 years. Assuming the population standard deviation is 11, what is the 95% confidence interval for true population mean?

A data set includes 106 body temperatures of healthy adult humans having a mean of 98.7°F and a standard deviation of 0.66°F. Construct a 99​% confidence interval estimate of the mean body temperature of all healthy humans. What does the sample suggest about the use of 98.6°F as the mean body​ temperature?

Researchers from a certain country were interested in how characteristics of the spleen of residents in their tropical environment compare to those found elsewhere in the world. The researchers randomly sampled 91 males and 109 females in their country. The mean and standard deviation of the spleen lengths for the males were 10.9 cm and 0.9 cm, respectively, and those for the females were 9.8 cm and 1.1 cm, respectively. Determine a 95% confidence interval for the difference between mean spleen lengths of males and females in this country. Click here to view page 1 of the table of critical values of t. Click here to view page 2 of the table of critical values of t. Let population 1 be all males in the country and let population 2 be all females in the country. The 95% confidence interval for µ1 - 4½ is ( | D (Round to three decimal places as needed. Use ascending order.)

In a random sample of 20 boxes of cereal, the mean sodium content is 173.1 mg with a standard deviation of 43 mg. construct a 90 percent confidence interval estimate for the true value of sodium in cereal while interpreting the interval estimate.

The 95% confidence interval for the mean waiting time is closest to what?