The Cassette Recorder
One family wants to get through a tunnel.
Dad can make it in 1 minute, mom in 2 minutes, son in 4 and daughter in 5 minutes. Unfortunately, not more than two persons can go through the narrow tunnel at one time, moving at the speed of the slower one.
Can they all make it to the other side if they have a torch that lasts only 12 minutes and they are afraid of the dark?
Ah! Click here to read the solution.
First mom and dad – 2 minutes.
Dad comes back – 3 minutes, both children go to mom – 8 minutes.
Mom comes to dad – 10 minutes and they both get to their children – 12 minutes. 🙂
Related Brain Teaser:
Do they all have to be at the other end of the tunnel at the end of the 12 minutes or is if sufficient for each one of them to have made it to the other end at some point in the 12 minutes?
i solved it for 11 minutes.