4 An article in Computers in Cardiology (1993, p. 317) presents the results of a heart stress test in which the stress is induced by a particular drug. The heart rates (in beats per minute) of nine male patients after the drug is administered are recorded. The aver- age heart rate was found to be x = 102.9 (bpm) with a sample standard deviation of s = 13.9 (bpm). Find a 90% confidence interval on the mean heart rate after the drug is administered