Welcome to Weekly Whys! Every week, I will be sharing a fun riddle/brain puzzle with you all. Why? Why not? Just kidding: With virtual classes and tons of hours spent indoors, I thought a riddle or two would be a good way to kill some time. And it turns out, these riddles are pretty interesting, and I hope you find them entertaining as well :)
So without further ado, here is your riddle of the week!
The Problem (Courtesy of Popular Mechanics):
Four people are trying to cross a sketchy rope bridge in the middle of the night. Only two can cross at a time. They only have one flashlight, and so one person must bring it back across the bridge to the starting side before anyone else can cross. One person takes 1 minute to cross, another takes 2 minutes to cross, another takes 5 minutes to cross, and the last person takes 10 minutes to cross. Hypothetically, if the 2-minute person and the 5-minute person crossed together, that would take a total of 5 minutes (but someone needs to bring the flashlight back, resulting in 7 minutes spent if the 2-minute person returns with the light). Everyone needs to get across in 17 minutes or less, otherwise they will be ripped apart and consumed by zombies. So, how do you get everyone across in 17 minutes or less?
My Attempt:
I must admit, this definitely took a while to figure out. You can see my thought process, though quite illegible, down below!
The Solution/Explanation:
Here's a Ted-Ed YouTube video by Alex Gendler that walks you through the problem and explains the solution!
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