Athletes tend to have lower resting heart rates because training programs that build speed, fitness, muscle, and endurance also train their heart muscles to pump a higher volume of blood with each heartbeat. An athletic nutrition manufacturer is looking for the best supplements that take less variation of heartbeats to power a wellconditioned athlete during intense training as well as during rest. He measured 25 athletes’ heart rates and recorded them in the following:

Heart Rate (bpm)

61 63 64 65 65 67 71 72 89 73 74 75 77 79 80 81 82 86 83 83 84 85 86 95 95 Use the given data to assist the manufacturer to develop a 90% confidence interval estimate of the variance of heart rate.