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A shuttle transfers passengers from 5:30 to 22:30, on a route between an airport and 3 hotels. The shuttle departs the airport every hour on the hour and drops off passengers at the hotels always in the same order (airport->Sheraton->Hilton->Carlson) and with fixed travel times between station pairs:

Airport - Sheraton : 21 min
Sheraton - Hilton  : 5 min
Hilton - Carlson   : 4 min
Carlson - Airport  : 30 min

On Wednesday Eddie got on a shuttle from his hotel to the airport exactly 2 hours before his flight. To Eddie’s surprise, the ride to the airport took 8 minutes less than it took on the previous Thursday when he stayed at that same hotel and had to catch a 13:30 flight.

What time was Eddie’s flight on Wednesday?

Hint 1:

Note that the "same order" of stations refers only to dropping off passengers at the hotels.

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    $\begingroup$ How is that possible? You said the ride takes exactly the same time to get from his hotel to the airport each time. $\endgroup$
    – Shuri2060
    Commented May 28, 2016 at 13:04
  • $\begingroup$ What is a round hour? Does it mean on the hour? $\endgroup$
    – LeppyR64
    Commented May 28, 2016 at 13:22
  • $\begingroup$ @LeppyR64 yes, on X:00 $\endgroup$
    – Guy Z.
    Commented May 28, 2016 at 13:28
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    $\begingroup$ @JoeZ. it accidentally said 5 minutes less. the correct number is 8 minutes less, fixed it now. $\endgroup$
    – Guy Z.
    Commented May 28, 2016 at 20:25
  • 1
    $\begingroup$ @2012rcampion zero time, for the purpose of this puzzle. $\endgroup$
    – Guy Z.
    Commented May 28, 2016 at 20:49

1 Answer 1

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The bus actually travels both ways on the path between the airport and the hotels — the route is 30 minutes there and 30 minutes back for a reason. However, when it leaves Carlson, it never drops anyone off until it reaches the airport.

The normal schedule looks like this:

Airport    :00  (dropoff and pickup)
Sheraton   :21  (dropoff and pickup)
Hilton     :26  (dropoff and pickup)
Carlson    :30  (dropoff and pickup)
Airport   1:00

But since the shuttle bus starts at 05:30 every morning, it actually starts off at the Carlson hotel. On the first trip of the day only (from 05:30 to 06:00), it picks people up from all three hotels on the way to the airport, dropping them all off once it arrives, as a service to the early riders from the other two hotels who shouldn't have to wait a whole hour more for the shuttle bus.

Carlson    :30  (pickup only)
Hilton     :34  (pickup only)
Sheraton   :39  (pickup only)
Airport   1:00  (dropoff and pickup)

So if Eddie lives at the Hilton, he will board the bus at 05:34 and arrive at 06:00, for a trip time of 26 minutes. Since he boarded the bus at 05:34, his plane is scheduled to leave at 07:34.

But for subsequent trips, it will go from Carlson straight to the airport without any more pickup stops because it has already visited the hotels a short time earlier, and visits each location every hour on the specified minutes. So if Eddie was catching a 13:30 flight, he'd have to board the bus at 11:26 to arrive at 12:00, for a trip time of 34 minutes, which is 8 minutes more than if he had boarded the first bus of the day as above.

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  • $\begingroup$ And the last trip of the day would be from 22:00 to 22:30, dropping people off at the hotels only, and not picking anybody up. $\endgroup$
    – user88
    Commented May 28, 2016 at 22:06
  • $\begingroup$ interesting actually very good haha I like it $\endgroup$
    – Adit Kirtani
    Commented May 29, 2016 at 9:28

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