Logic Puzzles

Ray Whitcombe is found dead in his office at his desk. The police have narrowed the suspects down to three people: Mrs. Barbara Whitcombe, Ray's wife; Mr. Jason McCubbins, Ray's business partner; and Mr. Harold Nichols, Ray's best friend. All three visited Mr. Whitcombe the day of his murder, but all three provide the police with stories of explanation as to the reason for their visit. Police found Mr. Whitcombe with his wrist watch still on his right arm, a torn up picture of his wife laying on the floor beside the trash can, and an ink pen in his right hand. On the desk, the police found a name plate, a telephone that was off the hook, and a personal calendar turned to the July 5th page with 7B91011 written on it. After examining this evidence, the police knew their suspect. Who was it?

There is a lamp inside a photography darkroom. When the darkroom door is closed, it is impossible to tell from outside the room whether or not the lamp is on. There are two switches outside the door of the darkroom. One or both of the switches may control the lamp. It also could be that neither of the switches control the lamp. All you know is that the light bulb is currently off and that the lamp and bulb are in working condition. The darkroom door is closed and once you open the door you cannot touch either of the switches. If you can only open the dark-room door one time, how can you tell which switches, if any, control the lamp?

A pet shop owner had a parrot with a sign on its cage that said "Parrot repeats everything it hears." A young man bought the parrot and for two weeks he spoke to it and it didn't say a word. He returned the parrot but the shopkeeper said he never lied about the parrot. How can this be?

A girl meets a lion and unicorn in the forest. The lion lies every Monday, Tuesday and Wednesday and the other days he speaks the truth. The unicorn lies on Thursdays, Fridays and Saturdays, and the other days of the week he speaks the truth. “Yesterday I was lying,” the lion told the girl. “So was I,” said the unicorn. What day is it?

This “burning rope” problem is a classic logic puzzle. You have two ropes that each take an hour to burn, but burn at inconsistent rates. How can you measure 45 minutes? (You can light one or both ropes at one or both ends at the same time.)

A man went on a trip with a fox, a goose and a sack of corn. He came upon a stream which he had to cross and found a tiny boat to use to cross the stream. He could only take himself and one other - the fox, the goose, or the corn - one at a time. He could not leave the fox alone with the goose or the goose alone with the corn. How does he get all safely over the stream?

If you’ve got me, you want to share me; if you share me, you haven’t kept me. What am I?

There are three crates, one with apples, one with oranges, and one with both apples and oranges mixed. Each crate is closed and labeled with one of three labels: Apples, Oranges, or Apples and Oranges. The label maker broke and labeled all of the crates incorrectly. How could you pick just one fruit from one crate to figure out what’s in each crate?

Jordan is leaving from a small town in Wyoming and hiking through the wilderness to a post where he will spend the summer. The hike will take Jordan six days. One man can only carry enough food and water for four days. Jordan cannot take a mule or any other animal to haul his food and water, because there will be insufficient food and supplies for the animals at his destination. How can Jordan make it to his destination?

Picture three boxes containing fruit. The first box is marked peaches, the second is marked oranges, and the third box is marked peaches and oranges. Each of the boxes is labeled incorrectly. How could you label each box correctly if you were allowed to select only one fruit from one of the boxes?