2.2 A "Real" Real-World Problem

Professor Richard Tapia of Rice University, one of the authors of this text, wanted to schedule a three-day business trip from New York City to Lausanne, Switzerland. He informed his travel agent that he needed to be in Lausanne by noon on Wednesday, June 23 for a luncheon and that he would like to be back in New York by 5:00 PM the following Saturday. Table 2.1 shows the flight information the travel agent faxed to Professor Tapia. The arrival and departure times listed in the schedule are local times in the respective cities. The flight from New York leaves at 7:50 PM and arrives in Geneva at 9:30 AM, leaving time to travel via ground transportation from Geneva to Lausanne.

Flight Number	Origin	Destination	Travel	Departure Time	Arrival Time
139	JFK	GVA	23 June 1999	19:50	09:30
123	GVA	JFK	26 June 1999	12:15	14:40

For medical reasons, Professor Tapia needed to know how much time he would actually be in flight. That is, he needed to know how long it would take to get from New York to Geneva. Although he had a nonstop flight, the information provided was not enough to allow him to determine immediately the length of time he would be in the air. In order to compute the actual duration of the flight, Professor Tapia needed to correct the local times by taking into consideration the difference in time zones. He knew that when he traveled from west to east, the time would be one hour later for each time zone crossed; but he didn't know how many time zones there are between the two cities.