A college dean wants to determine the average time it takes a student to get from one class to the next. Preliminary studies have shown that it is reasonable to let o = 1.5 minutes (the standard deviation of class travel times). What is the sample size which should be examined if the dean wants to assert with a probability of 95% that his estimate, the mean time of the random sample, will have a margin of error no more than 0.25 minutes (in either direction)? Choose the closest answer. 72 or more, but not less O 200 or more, but not less O 81 or more, but not less O 139 or more, but not less