A random sample of 16 graduates of a certain secretarial school typed an average of 76.7 words per minute with a standard deviation of 8.2 words per minute. Assuming a normal distribution for the number of words typed per minute, find a 90% confidence interval for the average number of words typed by all graduates of this school. Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. Click here to view page 1 of the table of critical values of the t-distribution. Click here to view page 2 of the table of critical values of the t-distribution. ..... The confidence interval is

The heights of a random sample of 40 college students showed a mean of 169.9 centimeters and a standard deviation of 7.4 centimeters. (a) Construct a 98% confidence interval for the mean height of all college students. (b) What can we assert with 98% confidence about the possible size of our error if we estimate the mean height of all college students to be 169.9 centimeters? Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. Click here to view page 1 of the table of critical values of the t-distribution. Click here to view page 2 of the table of critical values of the t-distribution.

A random sample of 12 graduates of a certain secretarial school typed an average of 82.6 words per minute with a standard deviation of 8.1 words per minute. Assuming a normal distribution for the number of words typed per minute, find a 95% confidence interval for the average number of words typed by all graduates of this school. Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. Click here to view page 1 of the table of critical values of the t-distribution. Click here to view page 2 of the table of critical values of the t-distribution. The confidence interval is <μ< (Round to two decimal places as needed.)

A data set includes 103 body temperatures of healthy adult humans having a mean of 98.5°F and a standard deviation of 0.61°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? Click here to view a t distribution table. Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. What is the confidence interval estimate of the population mean µ? (Round to three decimal places as needed.) What does this suggest about the use of 98.6°F as the mean body temperature? O A. This suggests that the mean body temperature is significantly higher than 98.6°F. O B. This suggests that the mean body temperature could very possibly be 98.6°F. OC. This suggests that the mean body temperature is significantly lower than 98.6°F.