Logic Riddles

 
Which Path (medium)

Question: You are walking down a path until there is a fork in the road. One side is the good path and the on the other side is the bad path. However you don't know which one is which. Both paths have identical twins guarding the paths. One guard tells the truth, the other lies all the time no matter what. But still you don't know which one tells the truth or which one tell lies. If you want to to go to the good path, what question should you ask the guards


By Martin Gardner

Question: You are in a room with two metal rods and no other metal. One of them is magnetized and the other is not.

How can you determine which one is magnetized and which is not?

Question: There are 100 passengers boarding a 100 passenger airplane. When passenger 1 gets onto the plane, he is dissoriented, so he randomly picks a seat. Each of the remaining passengers (2, 3, 4, etc.) get onto the plane and take their seat if it is available or picks one of the remaining seats at random if it is not.

What is the chance that the last passenger (passenger 100) will get his seat?

Question: A king is on a cross-sea voyage and as soon as they get off of their boats he spots the most beautiful elephant he has ever seen. He decides to take it home, but first, he wants to know its weight.

The largest scale they brought only goes up to 50 pounds. The king demands that his smartest scholar must come up with a solution or pay the consequences. After several days he finally comes up with an answer.

Question: There are 3 men, two Chimps, and one Gorilla on one side of a river:

  • They have a boat but only the men and the Gorilla can row the boat across, so there must always be a human and/or Gorilla on the boat.
  • The boat can only carry two people/monkeys.
  • If monkeys and humans are together on one side of the river there must be as many or more people than monkeys for the men's safety.
How can all men and monkeys make it to the other side?