na random sample of 21 people, the mean commute time to work was 32.5 minutes and the standard deviation was 7.1 minutes. Assume the population is normally istributed and use a t-distribution to construct a 99% confidence interval for the population mean u. What is the margin of error of µ? Interpret the results. The confidence interval for the population mean u is ( A D- Round to one decimal place as needed.) The margin of error of u is. Round to one decimal place as needed.) Interpret the results. O A. With 99% confidence, it can be said that the commute time is between the bounds of the confidence interval. O B. It can be said that 99% of people have a commute time between the bounds of the confidence interval. O C. With 99% confidence, it can be said that the population mean commute time is between the bounds of the confidence interval. O D. If a large sample of people are taken approximately 99% of them will have commute times between the bounds of the confidence interval.

Sales personnel for Skillings Distributors submit weekly reports listing the customer contacts made during the week. A sample of 85 weekly reports showed a sample mean of 18.5 customer contacts per week. The sample standard deviation was 5.4. Provide 90% and 95% confidence intervals for the population mean number of weekly customer contacts for the sales personnel. 90% confidence interval, to 2 decimals: 95% confidence interval, to 2 decimals:

The mean change in muscle thickness observed after a 4-week training regimen was 4 mm, and the 95% confidence interval (CI) for mean change was (-0.5, 8.5). Which is the best scientific conclusion for the effectiveness of this regimen ?

A sample of 106 body temperatures was taken and the mean was 98.2 degrees F. The population standard deviation is 0.62 degrees.  Use a 0.05 level of significance to test the claim that the average body temperature is actually different than 98.6 degrees F.  Find the 95% confidence interval of the mean temperature and compare your results.

You want to estimate the mean weight of quarters in circulation. A sample of 60 quarters has a mean weight of 5.682 grams and a standard deviation of 0.061 gram. Use a single value to estimate the mean weight of all quarters. Also, find the 95% confidence interval for the average weight of all quarters. The estimate for the mean weight of all quarters is (Round to three decimal places as needed.) grams. Find the 95% confidence interval for the mean weight of all quarters. grams < p< grams (Round to three decimal places as needed.)

The mean and standard deviation of Carbon concentration is 5 mg/L and 2 mg/L based on 25 samples from a river. The mean and standard deviation of Nitrogen concentration is 7 mg/L and 3 mg/L based on 35 samples from the same river. The experimenter wants to answer the question if the Nitrogen concentration is higher than the Carbon concentration. Which of the following methods do you use? Z-test, Default Procedure Z-test, Pooled Variance Procedure T-test, Pooled Variance Procedure T-test, Default Procedure

Sales personnel for Skilling Distributors submit weekly reports listing the customer contacts made during the week. A sample of 15 weekly reports showed a sample mean of 19.5 customer contacts per week. The sample standard deviation was 5.2. Provide a 90% confidence interval for the population mean number of weekly customer contacts for the sales personnel.

We want to estimate the mean distance travelled to work by employees of a large manufacturing firm. Past studies indicate that the variance of these distances is 4.0 km2and that the distances follow a normal distribution. How many employees should be chosen at random and polled if the estimated mean distance is to be within 0.1 km ofthe true mean with a confidence level of 95%?