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9. Men have pulse rates that are normally distributed with a mean of 72.1 beats per minute and a standard deviation of 9.7 beats per minute. If a group of 11 men are picked at random, find the probability that: a) the average pulse rate of the men is greater than 75 beats per minute. b) the average pulse rate of the men is lower than 60 beats per minute. c) the average pulse rate of the men is between 65 and 75 beats per minute