A lawyer commutes daily from his suburbs home to his midtown office. The average time for a one-way trip is 24 minutes with a standard deviation of 3.8 minutes. Assume the distribution trip times to be normally distributed.
The lawyer calculates his average commuting time for one five day work week and obtains 27.2. Assuming this to be a random sample, what is the probability a weekly average is 27.2 or less?