Can you solve the bridge riddle? – Alex Gendler

Can you solve the bridge riddle? – Alex Gendler


Taking that internship
in a remote mountain lab might not have been the best idea. Pulling that lever with the skull symbol
just to see what it did probably wasn’t so smart, either, but now is not the time for regrets because you need to get away
from these mutant zombies fast. With you are the janitor,
the lab assistant, and the old professor. You’ve gotten a headstart,
but there’s only one way to safety: across an old rope bridge
spanning a massive gorge. You can dash across in a minute, while the lab assistant takes two minutes. The janitor is a bit slower
and needs five minutes, and the professor takes
a whole ten minutes, holding onto the ropes
every step of the way. By the professor’s calculations, the zombies will catch up to you
in just over 17 minutes, so you only have that much time
to get everyone across and cut the ropes. Unfortunately, the bridge can only hold
two people at a time. To make matters worse, it’s so dark out that you can barely see, and the old lantern you grabbed on
your way only illuminates a tiny area. Can you figure out a way
to have everyone escape in time? Remember: no more than two people
can cross the bridge together, anyone crossing must either
hold the lantern or stay right next to it, and any of you can safely wait in the dark
on either side of the gorge. Most importantly, everyone must be
safely across before the zombies arrive. Otherwise, the first zombie could step on
the bridge while people are still on it. Finally, there are no tricks to use here. You can’t swing across, use the bridge as a raft, or befriend the zombies. Pause the video now
if you want to figure it out for yourself! Answer in: 3 Answer in: 2 Answer in: 1 At first it might seem
like no matter what you do, you’re just a minute or two short of time,
but there is a way. The key is to minimize the time wasted
by the two slowest people by having them cross together. And because you’ll need to make
a couple of return trips with the lantern, you’ll want to have the fastest people
available to do so. So, you and the lab assistant quickly
run across with the lantern, though you have to slow down
a bit to match her pace. After two minutes, both of you are across, and you, as the quickest,
run back with the lantern. Only three minutes have passed. So far, so good. Now comes the hard part. The professor and the janitor take
the lantern and cross together. This takes them ten minutes since the janitor has to slow down
for the old professor who keeps muttering that he probably shouldn’t
have given the zombies night vision. By the time they’re across,
there are only four minutes left, and you’re still stuck
on the wrong side of the bridge. But remember, the lab assistant
has been waiting on the other side, and she’s the second fastest of the group. So she grabs the lantern
from the professor and runs back across to you. Now with only two minutes left,
the two of you make the final crossing. As you step on the far side of the gorge, you cut the ropes
and collapse the bridge behind you, just in the nick of time. Maybe next summer,
you’ll just stick to the library.

100 thoughts on “Can you solve the bridge riddle? – Alex Gendler”

  1. Im actually doing this here.
    Hold the old man and just sprint since he said nothing about weight.
    1 minute.
    Run back and grab the janitor.
    3 minutes.
    Then run back and grab the girl
    5 minutes.
    WOWOWOWOWOWO SO HARDDDD

  2. why didnt the professor and the janitor go together? The condition was that the professor held onto the rope every step of the way, so you could just let them go first and clear the bridge and go across second for a total time of 12 minutes?

  3. So how can I be certain, the lab assistant won't panic and will return with the lamp? I guess it's essentiel to keep the scissors at all times, so you won't be left behind.

  4. Hmmm….if I was in this situation, I would refer to the Darwinian evolutionary theory and think ‘Out of this group, who will leave the most copies of itself in successive generations.’ The answer is the lass and I… sorry paps, survival of the fittest etc.

  5. What if we don't have the stop clock.so I have a answer for this riddle
    1.make professor and I cross
    2.i am acting as a time clock that when I crossed the bridge for 10 times,all came to know that professor had crossed.
    3.The time endured is 10minutes
    4.make lab assistant and I cross .when I crossed bridge for 2 times ,lab assistant had crossed
    5.then the time endured is 12 min
    6.then me and janitor crossed the bridge in 5 min .
    7.when I came to know that janitor had crossed .I will cut the rope
    8.the time endured is 17min
    9.finally,we all get rid off zombies

  6. 1+2 -> 1back -> 5+10 -> 2back -> 1+2 -> sum of time to cross is 2+1+10+2+2= 17min. (If there are more people (>2), to repeat 1+2 and 1 back )

  7. Maybe two people can go across one person takes the lantern then goes back to take another one while illuminating the area the fastest person and then that person take another person and they both return then the fastest person goes back again and takes another person so basically: 2 people go across the fastest person takes the lantern and goes and takes another person and then the same thing goes with the last person

    Edit: wow i had it right
    Edit 2: I am smort

  8. No one :
    Literally No one:
    Me : If that guy would have given piggy back ride to each of them…They can be safe in just 5 minutes.

  9. Just over 17 m could mean 18 m so I prob take the risk also the sizing is ridiculous 10 minutes to cross such a small bridge lol

  10. You = Curella De’vil (101 Dalmatians 2 patch’s London adventure version)
    Old professor Uh I gave them night vision
    You: SACRIFICES MUST BE MADE!!!!

  11. Me: Well, I cant figure this out. Someone is not going to make it. Who is the slowest person
    Professor: I am
    Me:
    Professor:
    Me: (from the other side)

  12. I actully guessed it!!!! First the 1 and 2 min go then 1 min goes back and hands the lanterns to the 5 and 10 min to go down the bridge and then the 2 min will go back and get across with me. It will be exactly 17 min

  13. The answer is for you and the lab assistant go to the other side without the lantern because you aren't afraid of the dark and then the janitor and professor go with the lantern boom 5 minutes to spare

  14. My solution: I carry the old guy on my back, which ofc slows me down so I use 3 minutes… That leaves 14 minutes. I run back, 13 minutes. Walk with the janitor guy, 7 minutes. Run back, 6 minutes. Walk with the girl, boom 4 minutes left.

  15. Me and lab assistant- 2minutes, I walk give lap to old man and 5 minutes guy – 3 minutes, they walk- 13 minutes, lab assistant get lamp and walk across a bridge -15 minutes, we go back 17 minutes. Cut the rope and dance!

  16. I can do better. I let the prof and janitor walk. So thats 10 minutes. Then i ran and get the lantern= +2 mins. Then i walk with assistant +2 mins. So total of 14mins. 😉

  17. Just shuffle along the ropes like sideways weird monkey bars. All at the same time. You won't collapse the bridge anyway, 'cause you're not touching the ground.

  18. you carry the proffesor and the two of you cross the bridge(2mins). get back give the lamp to the lab assistant(1minute) and her and janitor cross the bridge(5mins). lab assistant goes to you and give the lamp(2mins)cross the bridge together(2mins).

  19. There are SO many ways you could do this while reducing time, all those restrictions are everything you claim to be wrong in the education system

  20. I don’t understand why they need the light, it’s a rope bridge with handrails, you don’t need to see just feel your way along. Following that logic, send the janitor and the professor first each at their own pace. When the janitor reaches the other side( or six minutes) yell back and the professor can pass the message back, send the assistant wait 3 minutes then cross yourself, everyone across in 10 minutes. I added extra minutes to the cross times to make sure there are only two people on the bridge at one time.

  21. Lol there no weight restriction on the bridge just a number restriction… so if you carry someone it can still be considered one person…

  22. Alternative action, The young guy carries the old guy piggy back and repeats the process which in total time should be about 8 minutes.

  23. why do everybody need a light the bridge goes one way just walk in the direction that it's going and everybody gets across with 5 minutes to spare period

  24. I mean ok maybe the lantern is not bright enough to iluminate the whole path but what if you just make the two slow persons go first (10 minutes) and then they make a sign with the lantern on the other side of the bridge to make sure they are no longer on the bridge, THEN you cross with the lab assistant (even without the lantern to directly iluminate the path you could tell how far away you are from them depending on its brightness) and since you are the two fastest you could go at a moderate speed and reach the other end at less than 7 minutes, also the bridge would break with the weight of the zombies

  25. Lab assistant and you 2 min to 1 min fro total 3
    Janitor and Prof take 10 min and LA 2 min fro total 15
    You and LA take 2 min total 17

  26. Shoot the professor in the knees … you and the cute chick go across and cut the ropes … get married and start a family … send the kids to business college …

  27. Wait. Couldn't you save even more time? Have Prof. and Janitor cross (10min), then Fast Guy cross (11min), get lantern, and cross back (12min), and finally cross over again with Lab Assistant (14min), leaving you with three minutes to spare. Am I wrong?

  28. Zombies will catch up in 17 mins, someone can cross with professor, that's 10 mins max, someone can cross with the janitor that's 5 mins max so 15 mins and everyone is across safely, there solved it right away

  29. Here is the solution: The professor goes first, holding to the ropes of the bridge all the way, like a blind man. After 5 minutes, take the janitor and cross with him the bridge. By the time you reach the end, the professor has arrived there too. Come back, grab the assistant, with another 2 minutes, you are all accross, total 13 minutes.

  30. Give the old guy a piggyback ride. Look at him, he’s literally just spine, he’s probably not that heavy. Geez, someone needs to feed him afterwards.

  31. I figured since the old man was going to hold the rope the whole time, he didn't need the light, and figured the 2nd slowest could go with him holding the rope, then me and 2nd fastest go for a time of 12 minutes

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