Question

The scheduled arrival time for a flight from Washington DC to Istanbul is 7AM. Sometime before landing, the cabin crew serves breakfast to passengers. Some passengers eat fast, others slowly, some eat everything on the plate, others eat only a few items. In short, the time taken for a passenger to finish their breakfast is uncertain. Let that time be X minutes. X is normally distributed with a mean of 20 minutes and a standard deviation of 7 minutes. The flight attendants collect all breakfast trays 30 minutes before arrival so that they can prepare the cabin for landing.

a. At what time should the flight attendants serve breakfast so that there is only a 10% chance that someone will not be able to finish their breakfast before the trays are collected?

b. If the flight attendants serve breakfast 60 minutes before arrival time, what percentage of passengers will not be able to finish their breakfast prior to the trays being collected?

c. On a particular flight, the plane was running in to turbulence from time to time. They were only able to serve breakfast 50 minutes before landing. Unfortunately, 20 minutes later, the plane again ran into turbulence and the trays had to be collected. What percentage of passengers could not finish their breakfast?

Answer 1