# Pilots who cannot maintain regular sleep hours due to their workschedule often s

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Pilots who cannot maintain regular sleep hours due to their workschedule often suffer from insomnia. A recent study on sleepingpatterns of pilots focused on quantifying deviations from regularsleep hours. A random sample of 27 commercial airline pilots wasinterviewed and the pilots in the sample reported the time atwhich they went to sleep on their most recent working day. Thestudy gave the sample mean and standard deviation of the timesreported by pilots with these times measured in hours aftermidnight. (Thus if the pilot reported going to sleep at 11p.m.the measurement was -1.) The sample mean was 0.6 hours and thestandard deviation was 1.9hours. Assume that the sample is drawnfrom a normally distributed population. Find a 99%confidenceinterval for the population standard deviation that is thestandard deviation of the time (hours after midnight) at whichpilots go to sleep on their work days. Then complete the tablebelow.

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