An airline claims that its average taxi time is 15 minutes, and the standard deviation is 1.4 minutes. The taxi time has a bell/mound shape distribution. On a flight with this airline, you observe that the taxi time is 20 minutes. Calculate the z score for the taxi time. Is 20 minutes unusual?
Yes, 20 minute is unusual because it is more than 2 standard deviations above the mean.
No, 20 minutes is not unusual because it is within 15 minutes of the mean.
No, 20 minutes is not unusual because it is within 2 standard deviations of the mean.
Yes, 20 minute is unusual because it is more than 1.4 minutes above the mean.