According to the Census Bureau's 2002 American Community Survey, the average travel time to work of workers 16 years and over living in Boston, MA, who did not work at home, was 28.2 minutes with a standard deviation of 0.79 minutes. A sample of 35 commute times is taken. What is the probability that the mean commute time is at least 28 minutes? We cannot assume that the data comes from a normal distribution.

Question

According to the Census Bureau's 2002 American Community Survey, the average travel time to work of workers 16 years and over living in Boston, MA, who did not work at home, was 28.2 minutes with a standard deviation of 0.79 minutes.  A sample of 35 commute times is taken.  What is the probability that the mean commute time is at least 28 minutes?  We cannot assume that the data comes from a normal distribution.