Logic Puzzles

Puzzles that can only be solved by thinking logically.

Three people

There are three people (Alex, Ben and Cody), one of whom is a knight, one a knave, and one a spy. The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth. Alex says: “Cody is a knave.” Ben says: “Alex is a knight.” Cody says: “I am the spy.” Who is the knight, who the knave, and who the spy?

Answer
Score visitors
Average: 8 (1 vote)

A fork in the road

You’re at a fork in the road in which one direction leads to the City of Lies (where everyone always lies) and the other to the City of Truth (where everyone always tells the truth). There’s a person at the fork who lives in one of the cities, but you’re not sure which one. What question could you ask the person to find out which road leads to the City of Truth?

Answer
Score visitors
Average: 8 (1 vote)

Days

The day before two days after the day before tomorrow is Saturday. What day is it today?

Answer
Tags
Score visitors
Average: 8 (1 vote)
Kind of riddle

Looking at eachother

Jack is looking at Anne. Anne is looking at George. Jack is married, George is not, and we don’t know if Anne is married. Is a married person looking at an unmarried person?

Answer
Score visitors
Average: 8 (1 vote)

Ducks

There are two ducks in front of a duck, two ducks behind a duck and a duck in the middle. How many ducks are there?

Answer
Tags
Score visitors
Average: 8 (1 vote)
Kind of riddle

All walls within face south

A man goes into a cabin deep in the country. All walls within this cabin face south and are made of wood. A bear walks by the window. What color is he?

Answer
Score visitors
Average: 7 (1 vote)
Kind of riddle

Money talks

A wealthy man named Richard Ellis had been counting his money. When he finished, he accidentally left a $100.00 bill on his desk. But when he returned for it a short while later, it was gone. Only two other people could have seen the bill. One was the maid; the other was the butler. The maid told him that she had hidden it for safe-keeping under a green book that was on the desk. But when they looked the bill was not there. The butler said he had found the bill where the maid had left it. He had placed it inside the book, where he thought there was less chance that somebody would find it. He had written down the page numbers so that he would not forget them. The bill was between pages 35 and 36, he said. But when they looked, there was no money in the book. After Mr. Ellis had talked to the maid and the butler, he called the police. He knew who had taken the money. Who was it, and how did he know?

Answer
Score visitors
Average: 7 (1 vote)
Kind of riddle

Cutting down trees

Dynamite is a tool that can be used to cut down trees. To cut a tree 18 inches in diameter requires five sticks of dynamite: one on the north, south, east and west sides of the tree, and the fifth stick on the side to which the tree should fall. During construction of a dam, a tree 18 inches in diameter was completely covered by water. Since the treetop was fouling the boat's propellers, it had to be cut down. A diver went down and put a stick of dynamite on the four sides of the tree. Since the current is flowing south at 2 knots per hour, on which side of the tree would you instruct the diver to put the fifth stick of dynamite if you wanted the tree to fall north?

Answer
Score visitors
Average: 7 (1 vote)
Kind of riddle

Nine minutes

How can you measure nine minutes with have two hourglasses, one four minute and one seven minute?

Answer
Score visitors
Average: 6 (1 vote)
Kind of riddle