Crossing the Bridge - A Puzzle

[Tom Rankin]

(If you've seen this before, keep your mouth shut!)

Mats, Chip, Paradox, and I are hiking together at night when we come to a bridge. The bridge is very narrow and looks REALLY rickety. We decide that 2 at a time can cross safely, but no more. Then we discover that we only have 1 headlamp, DOH! And we MUST use the headlamp to cross the bridge! If they were alone, Mats could cross the bridge in 1 minute, Chip in 2, Paradox in 5, and myself in 10. Whichever 2 people cross the bridge MUST cross together! The headlamp must be carried back over each time, (it's way too far to throw, and we don't want to lose it or bust it!).

Given these constraints, what is the shortest time we can cross the bridge?

(If you've seen this before, keep your mouth shut!)

 

[bikehikeskifish]

What if the ranger takes the bridge down in the middle of the puzzle?

(I know the answer)

Tim

 

[Stash]

Make it a poll?

I've got a thought but can you make it a poll before anyone answers? half a dozen possible responses. Might make it more interesting...

 

[RollingRock]

This is probably a trick question but here is my reply:

Mats and Chip together =2. Mats returns for Paradox =1. They cross together =5. Mats returns for Tom =1. They cross together =10. Total is 19 minutes.

 

[Rik]

Mats goes across with the light and mini keg. Tom and others fall over each other crossing in the dark. Probably about 2 minutes total.

 

[bikehikeskifish]

Total is 19 minutes.

You can do it in less time than that.

Tim

 

[Chip]

1 minute. We wouldn't blame Mats for leaving us behind.

 

[David Metsky]

Mats and Chip go over - 2 minutes
Mats comes back - 1 minute
Paradox and Tom go over - 10 minutes
Chip comes back - 2 minutes
Chip and Mats go over - 2 minutes
Total time - 17 minutes

 

[MichaelJ]

Won't the fox eat the chicken if they're on the bridge at the same time? Oh, wait, wrong puzzle...

 

[bikehikeskifish]

Mats and Chip go over - 2 minutes
Mats comes back - 1 minute
Paradox and Tom go over - 10 minutes
Chip comes back - 2 minutes
Chip and Mats go over - 2 minutes
Total time - 17 minutes

Correct. Tom paraphrased today's Mensa page-at-a-glance puzzle, something we're both big fans of.

Tim

 

[Barkingcat]

Won't the fox eat the chicken if they're on the bridge at the same time? Oh, wait, wrong puzzle...

Yah...and the ranger will make a sign for Owl's Head out of the bridge remnants...

 

[NewHampshire]

Wait, but y'all assume Matts does not stop in the middle on the bridge for a few push-ups!

Brian

 

[Paradox]

Oh no! Where's Laurie?!?! Laurie!! Laurie!!! Laurie!!!! What the...?

 

[Tom Rankin]

Oh no! Where's Laurie?!?! Laurie!! Laurie!!! Laurie!!!! What the...?

I knew we forgot someone!

 

[Nessmuk]

Correct. Tom paraphrased today's Mensa page-at-a-glance puzzle, something we're both big fans of.

Tim

Sounds like someone is into a discipline called "operations research". It was a fun course. Here's a pdf download the big dirty analysis of the solution.

 

[brianW]

I thought the bridge was blown up.

 

[Neil]

The best I could do was 3 hours and 22 minutes because the headlamp turned out to be a miniature hookah pipe.

 

[walker]

Time it takes for F&G to fine you $$$

Now,figure how long it takes for Fish and Game to fine you for hiking at night with only one source of light and no map.
If you had a map, you would have noticed the bridge that should only be attempted in day light.
Not reading the trail description, which notes the bridge has problems and will be taken down in the future because it's in a Official Wilderness Area will also be held against you.

Forget the bridge, just send the F&G a check. NOW PLEASE!!

Life free and Hike...WALKER