Logic Puzzles - Puzzle Stream

Easy Puzzles:

Watch Where You Step

Why are manholes generally round, as opposed to square-shaped?

A round manhole is the same width from the center all around versus a square one, which is not. A square manhole can only be placed in a few configurations without falling through the hole.

Missing Money

Three men order meals at $5 each for a total of $15. The waiter takes the check to the chef who, recognizing the patrons as his friends, asks the waiter to return $5.

Being dishonest, the waiter gives $1 to each of the men and pockets $2. Each of the men, essentially paid $4 for their meals but $4 x 3 plus the $2 pocketed equals $14. What happened to the other $1?

To see where the missing money is, you have to look at te receipts. The total they paid $15 minus the discount they got $3 is $12. This is equal to the Amount the owner received $10 plus the amount the waiter pocketed $2.

Wrong Bucket, but That's Okay

If you have a four and seven gallon bucket with no measuring marks, how would you measure out five gallons?

Fill the four and pour it into seven. Fill the four again and pour it into the seven. This should leave one gallon left. Empty the seven, pour the one gallon from the four into the seven, fill up the four and pour it into the seven to give you a total of five gallons.

Chicken Crossed the River

A chicken, bag of feed, wolf, and you are on one side of a river. If the chicken is left with the bag of feed, it will eat it. If the wolf is left with with chicken, the wolf will eat the chicken. How do you get everyone to the other side if you can only take one entity with you at a time?

Grab the chicken and take it over to the over side. Return without anything. Take the wolf or the feed to the other side and return with the chicken. Take the feed or the wolf over (whichever is not on this side of the river now) and return back with nothing. Finally, take the chicken over.

No Change too Little

You've inserted a coin into an empty bottle and closed it with a cork. How do you remove the coin without breaking the bottle or taking out the cork?

Simply push the cork in and shake the coin out.

Calendar This

Two cubes are arranged on a secretary's desk such that they can be used to represent every day of the month. What number is on each face of the cubes to make this happen?

One cube will have something like 0, 1, 2, 3, 4, 5 and 0, 1, 2, 6, 7, 8 on it. There is no 9 needed because the 6 can be turned around to represent it.

Who Hired the Electrician?

There are four switches in a hallway that can be turned on and off. One controls the light in the living room. The switch is off as are all of the others. You also don't know which switch controls the living room light. The other switches do nothing.

From the hallway, you can't see whether or not a light is going off in the living room.

Being able to flip switches as many times as you would like but only able to go into the room once before declaring which switch it was that turned on the light, how would you determine which switch controlled the living room light?

Turn on the last two switches (3 and 4) and leave them on for a while. After this time, quickly turn off 3 and on 2. Walk into the room. If the light bulb is dark and cool, then none of the switches you toggled turned on the light--switch 1 controls it. If the light bulb is lit and cool, then it was just turned on via switch 2. If the light bulb is dark but warm, then it was previously on--it's switch 3. Finally, if the light bulb is lit and warm, then it's been on the whole time--it's switch 4.

Master Chef

If you have a three and five unit measuring cup but you can't see the marks because you've used the cups so much, how do you measure out four units?

Fill the five and pour it into the three. This should leave two units in the five. Empty the three and pour the two units from the five into it. Fill the five up again and pour one unit into the three to leave four units in the five.

Dressing in the Dark

Twelve black socks and twelve white ones are in a drawer. Unable to see the socks, how many must be taken out to be sure that a pair matches?

Because socks are not sided, you can simply pull out three. One sock will be paired up.

Timed to Perfection

Two strings take exactly one hour to burn from either end. They burn at random rates though. How would you use the strings to measure 45 minutes?

Light both ends of one string and one end of the other. The string with both ends lit will expire after 30 minutes. Once this happens, you can light the other end of the string that only has one side lit. Once this string expires, 45 minutes will have elapsed.

Mismatched

Three boxes are in front of you. One says "Toys," another "Supplies," and the final, "Toys and Supplies." Knowing that each is labeled incorrectly, how do you label the boxes correctly if you can't look at the contents but can have someone pull an item out of one of them for you to see?

Have the other person pick from the box labeled "Toys and Supplies." If a toy comes out, this box can be labeled "Toys." If a supply comes out, it can be labeled "Supplies." The other boxes can be labelled accordingly by process of elimination.