The heights of a random sample of 60 college students showed a mean of 183.1 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 183.1 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) The confidence interval is < <] (Round to two decimal places as needed. A random sample of 12 graduates of a certain secretarial school typed an average of 78.9 words per minute with a standard deviation of 7.5 words per minute. Assuming a normal distribution for the number of words typed per minute, find a 99% 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 < <]. (Round to two decimal places as needed.)