A random sample of 18 graduates of a certain secretarial school typed an average of 83.6 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, compute the 90% prediction interval for the next observed number of words per minute typed by a graduate of the secretarial 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 prediction interval is ​
< (Round to two decimal places as needed.