Another Riddle

[Dragonboy]

I have got an interesting riddle for those that are interested.

Picture yourself a group of 4 people out in the bush.
In the middle of the night they reach a crappy looking rope bridge from which they expect only 2 persons max. can walk across at the same time.
Only it is so dark that they cannot even see the other side of the canyon they want to cross.

1. The party has only 1 flashlight from which the battery only has 17 minutes left and crossing the bridge without the flashlight is impossible.
2. Only 2 people max are allowed to walk across the bridge at the same time.
3. Considering that crossing the bridge without a flashlight is not possible 1 who has already crossed the bridge must return to meet with the other members left behind.
4. Both crossing persons walk the speed of the slowest.
5. All 4 people vary in walking speed.
Person no.1 is expected to reach the opposite side in 1 minute.
Person no.2 is expected to reach the opposite side in 2 minutes.
Person no.3 is expected to reach the opposite side in 5 minutes.
Person no.4 is expected to reach the opposite side in 10 minutes.

Who can tell me the combination in which the 4 persons have to walk back and forth in order for all to reach the other side before the battery of the flashlight is empty. (2 persons forth, 1 back)


Have fun

[Velea]

I like my answer....

The one minute and five minute people go last, and they just jump the last few feet when the battery runs out.

My husband told me no, though. That isn't a valid answer.

[Dragonboy]

Hehe... Trust me... It is possible.

[Oakleif]

Picture yourself a group of 4 people out in the bush.
In the middle of the night they reach a crappy looking rope bridge from which they expect only 2 persons max. can walk across at the same time.
Only it is so dark that they cannot even see the other side of the canyon they want to cross.

1. The party has only 1 flashlight from which the battery only has 17 minutes left and crossing the bridge without the flashlight is impossible.
2. Only 2 people max are allowed to walk across the bridge at the same time.
3. Considering that crossing the bridge without a flashlight is not possible 1 who has already crossed the bridge must return to meet with the other members left behind.
4. Both crossing persons walk the speed of the slowest.
5. All 4 people vary in walking speed.
Person no.1 is expected to reach the opposite side in 1 minute.
Person no.2 is expected to reach the opposite side in 2 minutes.
Person no.3 is expected to reach the opposite side in 5 minutes.
Person no.4 is expected to reach the opposite side in 10 minutes.

Who can tell me the combination in which the 4 persons have to walk back and forth in order for all to reach the other side before the battery of the flashlight is empty. (2 persons forth, 1 back)

*IF* the flashlight can light the entire width of the bridge from the center, then:
1. Person 1 and Person 2 step out on the bridge. Person 1 stops in the center of the bridge at t=1 min. Person 2 continues across the rest of the bridge and gets to the far edge at t=2 min.
2. Person 3 crosses all the way while Person 1 shines the light for him from the center of the bridge. Person 3 gets to the far edge at t=7 min.
3. Person 4 crosses to the center of the bridge while Person 1 waits for him, then they both contine to the far edge of the bridge and arrive at t=17 min.

[Dragonboy]

The flashlight has to go all the way from beginning to end and back to the beginning.

[velveeta]

person 1 takes person 4 first, then 3, then 2.
the flashlight will burn out halfway thru the last trip, but by then person 1 knows the way anyway.....

[C`gan]

Here's the order I see:
1 and 4 (10 minutes)
1 returns (1 minute) (flashlight off. After all, this now makes time number 4 he's been on the bridge, so he knows where to step)
1 and 3 (5 minutes)
1 returns (1 minute) (flashlight off)
1 and 2 (2 minutes)

Total elapsed time: 19 minutes. Total time with flashlight on: 17 minutes.

[Dragonboy]

nope... flashlight must always be on.

[Takora Drakan]

They use the flashlight to make a campfire, and then everyone grabs a stick and walks over the bridge. :P

[Zachyattacky]

I have pondered this for awhile ... and have come up with 3 solutions!

-After the flashlight burns out they shake it and it now has full charge! Yay

-They give person #4 a red bull, speeding up his time by 2 minutes...

-Person #1 is obviously on steriods seeing as he/she is 10 times faster than the slowest, thus can carry person #4 across the bridge in 8 minutes

Haaa HA

[Velea]

I say it isn't fair that you keep changing the rules on us, Dragonboy.

Given the original set of rules, there's some rather clever solutions that would work.

Though I'm not sure about the whole steroid thing, Zachy.

[Zachyattacky]

I say it isn't fair that you keep changing the rules on us, Dragonboy.

Given the original set of rules, there's some rather clever solutions that would work.

Though I'm not sure about the whole steroid thing, Zachy.

If we put our heads together and think... we can do it! Just here, lemme borrow some of your brain cells... >_>

Alright, fine, so maybe #4 is just injured or really really (really really really) [really] old... So maybe steriods are a big far fetched, I can respect your opinion

[peladon]

I have got an interesting riddle for those that are interested.

Picture yourself a group of 4 people out in the bush.
In the middle of the night they reach a crappy looking rope bridge from which they expect only 2 persons max. can walk across at the same time.
Only it is so dark that they cannot even see the other side of the canyon they want to cross.

1. The party has only 1 flashlight from which the battery only has 17 minutes left and crossing the bridge without the flashlight is impossible.
2. Only 2 people max are allowed to walk across the bridge at the same time.
3. Considering that crossing the bridge without a flashlight is not possible 1 who has already crossed the bridge must return to meet with the other members left behind.
4. Both crossing persons walk the speed of the slowest.
5. All 4 people vary in walking speed.
Person no.1 is expected to reach the opposite side in 1 minute.
Person no.2 is expected to reach the opposite side in 2 minutes.
Person no.3 is expected to reach the opposite side in 5 minutes.
Person no.4 is expected to reach the opposite side in 10 minutes.

Who can tell me the combination in which the 4 persons have to walk back and forth in order for all to reach the other side before the battery of the flashlight is empty. (2 persons forth, 1 back)


Have fun

Wait. The day will wake, and the sun will come.


Sephiranoth, called by some ShadowSeeker

[Takora Drakan]

Brilliant Peladon, no doubt.

[Dragonboy]

I say it isn't fair that you keep changing the rules on us, Dragonboy.

Given the original set of rules, there's some rather clever solutions that would work.

Though I'm not sure about the whole steroid thing, Zachy.

I was not aware I was changing the rules, its more like adding things I forgot to mention.

Allright I will try to make the rules more clear.

Rules:
- 1 flashlight - Shining time max 17 minutes.
- 4 persons must cross the bridge in the end (1min, 2min, 5min and 10min walktime).
- max 2 persons must go to the other side together. slowest persons time counts to total time.
- 1 person from the group already on the other side must come back the whole way (and will always count in total time) to:
A) pick up a new person.
B) give the flashlight to another in the group.
- All 4 persons must be on the other side at 17 minutes.

It is goint to be:
A. 2 cross (slowest walktime)
B. 1 back (persons time)
C. 2 cross (slowest walktime)
D. 1 back (persons time)
E. 2 cross (slowest walktime)

Total time would be 3 times slowest walktime and 2 times persons time.
Which combination would make the above total time 17 min.?

[Zachyattacky]

I betcha 50 grapes that we all hit ourselves over the head with a Rancor when one of us figures it out

[jerk-o]

A 10 + B 1 = 11 + C 5 = 16 + D 1 = 17 with 1 and 2 on the wrong side

A 5 + B 1 = 6 + C 2 = 8 + D 1 = 9 with 10 and 1 on the wrong side and not enough time to cross

A 2 + B 1 = 3 + C 10 = 13 + D 1 = 14 with 5 and 1 on the wrong side and not enough time to cross

So what am I missing?

[Zachyattacky]

So what am I missing?

You know...As far as I can tell you arent missing anything that the rest of us aren't, which is clearly the correct answer
But yeah, every way like that gets you 19... so I dunno :S

*looks at the google search bar, then bats himself on the nose* Baaaad Zach

[Steelclaw]

1,2 cross; 2 returns (4 mins so far)
5,10 cross; 1 returns (15 mins so far)
2,1 cross (17 mins total)

[awdz]

obviously steelclaw got it, but how about this...

start the 5 min & 10 min persons first, 10 min w/flashlight.
5 min finishes crossing, 1 min person crosses behind 10 min person who still has light on bridge
1 min person takes light back to 2 min person, and both cross over.

total time 13 min