This riddle is a little more difficult then the “find the heavy egg” … I think I got it from an compsci interview question.
Help The Band Cross The Bridge
There are 4 band members that are trying to get to their concert.. they are late – AND – they have to cross a bridge!
(don’t worry how this happened .. it just did, ok?)
If they’re going to make it to the concert on time, they have to cross the bridge in 17 minutes or less.
Here is where it gets complicated:
- It’s night time and they only have 1 flashlight.
- The bridge is old and narrow, so only 1 or 2 members can cross at any one time.
- The flashlight can provide enough light for either 1 or 2 band members, but whoever is crossing the bridge must have the flashlight or be with someone who has the flashlight.
- They figured out the only way to make this happen is to have 2 people cross the bridge, then send 1 person back with the flashlight.
- They can’t throw the flashlight.. the bridge is too long (nice try).
Meet the band members:
As stated before, there are 4 band members:
- Alex – Vocals – Takes 1 minute to cross the bridge
- Mark – Violin – Takes 2 minutes to cross
- John – Guitar – Takes 5 minutes to cross
- Chris – Drums – Takes 10 minutes to cross
Remember, 2 people can cross at once, but they will go at the slower persons speed!
So if Alex and John go across, it will take them 5 minutes.
If only Mark goes across, it will take him 2 minutes (because he doesn’t have to wait on anyone else).
How can they all make across the bridge in 17 minutes?
The format should look something like this:
Alex and John go across for 5min… Total: 5min
Alex brings the flashlight back for 1min… Total: 6min
Chris and Mark go across for 10min… Total: 16min
As you can see, with the example started above, it’s already been 16 minutes and there is still someone left on the other side.. they aren’t going to make the concert.
Your turn.. leave your questions, thoughts, and answer in the comments below.. good luck 🙂