4 hikers have to cross a bridge. The bridge wiill collapse in exactly 17 minutes. It is pitch black outside and they only have 1 flashlight between them. The hikers all cross at different rates; one can cross in 1 minute another crosses in 2 minutes, and the others cross in 5 and 10 minutes respectively. The group of 2 travels at the slower hikers rate. The hikers can only cross in groups of 2 at the most. Each group has to have the flashlight give to them by hand. No tricks allowed, such as 1 hiker carries another, they throw the flashlight, or they go halfway and shine the light, ect. Thanx for the help!
2007-12-12 08:47:51 · 4 answers · asked by Jenna F 2 in Science & Mathematics ➔ Mathematics
4 hikers have to cross a bridge. The bridge wiill collapse in exactly 17 minutes. It is pitch black outside and they only have 1 flashlight between them. The hikers all cross at different rates; one can cross in 1 minute another crosses in 2 minutes, and the others cross in 5 and 10 minutes respectively. The group of 2 travels at the slower hikers rate. The hikers can only cross in groups of 2 at the most. Each group has to have the flashlight give to them by hand. No tricks allowed, such as 1 hiker carries another, they throw the flashlight, or they go halfway and shine the light, ect. Thanx for the help!
ok, another one: You have a list of numbers from 0 to 100. How fast can you add them up without a calculator? What is the answer?
2007-12-12 09:36:46 · update #1
Mr. 1 Minute and Mr. 2 Minutes Cross = 2 minutes
Mr. 2 Minute Returns the Flashlight=2 minutes
Mr. 5 Minute and Mr. 10 Minute Cross = 10 minutes
Mr. 1 Minute Returns the Flashlight = 1 minute
Mr. 1 Minute and Mr. 2 Minutes Cross = 2 minutes
Total: 17 minutes
The trick is to optimize the double trips across the bridge rather than make Mr. 1 Minute always run back the flashlight.
2007-12-12 09:01:07 · answer #1 · answered by El Piripiripau 3 · 0⤊ 0⤋
Have 1 and 2 cross first --> 2 minutes
Have 1 return to the other side --> 1 minute
Have 5 and 10 cross next --> 10 minutes
Have 2 return to the other side --> 2 minutes
Have 1 and 2 cross for the final time --> 2 minutes
2 + 1 + 10 + 2 + 2 = 17 minutes
2007-12-12 08:52:57 · answer #2 · answered by Puzzling 7 · 2⤊ 0⤋
what's the question?
2007-12-12 08:58:45 · answer #3 · answered by nopowerhere 2 · 0⤊ 0⤋
whats the question????
2007-12-12 08:53:48 · answer #4 · answered by curiousperson 2 · 0⤊ 0⤋