Resting pulse rate is an important measure of the fitness of a person's cardiovascular system with a lower rate indicative of greater fitness. A random sample of 20 male students currently enrolled in the Faculty of Agriculture was selected and the mean pulse resting pulse rate was found to be 80 beats per minute with a standard deviation of 20 beats per minute. Assume that the resting pulses come from a normal distribution. Based on this information a 95% confidence interval for the true mean resting pulse rate of males would be