The nj department of highways wants to estimate the average number of the passenger cars that pass a busy intersection of r1 each day. the requirements are that the estimate be within t.10 cars per day of the population mean and that the investigators be 99% confident of the results. a similar study showed that the standard deviation to be 50 cars per day. how large a sample is required? a) 13 b) 67 c) 52 d) 161 e) 167