4 musicians are on one side of a bridge at night and need to
reach the other side in the next 16 minutes.
They only have 1 flashlight and so must travel in pairs accross
the bridge, with one person returning with the flashlight for the next pair.
Going across, the pairs must walk at the speed of the slowest person.
The 4 musicians take 1,2,5 & 9 minutes to cross the bridge
respectively.
How do they manage to do it?
This is not a trick question but one of resource management.
Originally posted by Thequ1ck 4 musicians are on one side of a bridge at night and need to
reach the other side in the next 16 minutes.
They only have 1 flashlight and so must travel in pairs accross
the bridge, with one person returning with the flashlight for the next pair.
Going across, the pairs must walk at the speed of the slowest person.
The 4 musicians take 1,2,5 & 9 mi ...[text shortened]... it?
This is not a trick question but one of resource management.
n.b there are 2 answers.
Solution I:
- 2 and 1 go over (2 min)
- 1 comes back (1 min)
- 9 and 5 go over (9 min)
- 2 comes back (2 min)
- 2 and 1 go over (2 min)
Total time = 16 minutes
Solution II:
- 2 and 1 go over (2 min)
- 2 comes back (2 min)
- 9 and 5 go over (9 min)
- 1 comes back (1 min)
- 2 and 1 go over (2 min)
Total time = 16 minutes
The main idea is to never waste time sending 9 or 5 back, and also to 'eliminate' the 5-minute guy from the addition.
Originally posted by BigDoggProblem Solution I:
- 2 and 1 go over (2 min)
- 1 comes back (1 min)
- 9 and 5 go over (9 min)
- 2 comes back (2 min)
- 2 and 1 go over (2 min)
Total time = 16 minutes
Solution II:
- 2 and 1 go over (2 min)
- 2 comes back (2 min)
- 9 and 5 go over (9 min)
- 1 comes back (1 min)
- 2 and 1 go over (2 min)
Total time = 16 minutes
The main idea ...[text shortened]... er waste time sending 9 or 5 back, and also to 'eliminate' the 5-minute guy from the addition.
Very good. Most people take many hours to solve that one.
The catch is understanding that the torch can be passed.
Originally posted by Thequ1ck 4 musicians are on one side of a bridge at night and need to
reach the other side in the next 16 minutes.
They only have 1 flashlight and so must travel in pairs accross
the bridge, with one person returning with the flashlight for the next pair.
Going across, the pairs must walk at the speed of the slowest person.
The 4 musicians take 1,2,5 & 9 mi ...[text shortened]... it?
This is not a trick question but one of resource management.
n.b there are 2 answers.
I haven't read any answers yet.
Heres mine,
2 & 1 = 2
2 = 2
5 & 9 = 9
1 = 1
2 & 1 = 2
Total = 16
Took a little while to figure out how to get 5 & 9 across together.
Originally posted by nickhawker Because i didn't scroll down and hence didn't see your post till afterwards. You see there is this thing called willpower, it's quite useful.
You must have a tiny monitor if you have to scroll down just to see the 2nd post in a thread...
Originally posted by BigDoggProblem You must have a tiny monitor if you have to scroll down just to see the 2nd post in a thread...
It is not so much the size of the monitor as its resolution setting. Plus, RHP has a rather wide top margin before the actual contents of the posts start. I see less than one half of the second post, with resolution set to 1024 x 768 (I know, I'm an old blind bat and have to have big text 🙂
Crossing the bridge - Hard riddle
19 Nov '05 21:24
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