You have a rope that burns in exactly 30 minutes. The rope doesn't burn at a uniform rate. How can you measure exactly 15 minutes using this rope?
Light the rope from both ends. When the flames meet, exactly 15 minutes will have passed.
Pick any number. Double it. Add 9. Subtract 3. Divide by 2. Subtract the original number. What number are you left with?
The number is always 3, regardless of the original number you picked.
A monkey, a squirrel, and a bird are racing to the top of a coconut tree. Who will get the banana first: the monkey, the squirrel, or the bird?
Answer: None of them, because you can't get a banana from a coconut tree.
What is made of water but if you put it into water it will die?
Answer: An ice cube
You have 7 apples. You need to distribute them among 7 people in such a way that each person gets 1 apple, but one apple must remain in the basket. How do you do it?
Give 1 apple to each of the first 6 people, and give the 7th apple along with the basket to the last person. This way, everyone gets an apple, and one apple remains in the basket.
What letter comes next in the following sequence. D R M F S L T_
Answer: D, each letter represents one note in the diatonic musical scale: Do, Re, Mi, Fa, Sol, La, Ti, Do
Why are manhole covers round?
Manhole covers are round so they can fall through the opening. A round cover cannot be turned sideways and dropped through its circular opening, unlike square or rectangular covers.
In my hand I have two coins that are newly minted. Together, they total 30 cents. One isn't a nickel. What are the coins?
Answer: A quarter and a nickel
What can be stolen, mistaken, or altered, yet never leaves you your entire life?
Answer: Your identity
Some try to hide, some try to cheat, but time will show, we always will meet. Try as you might to guess my name, I promise you'll know when you do claim. Who am I?
Death
They fill me up, and you empty me almost every day; if you raise my arm, I work the opposite way. What am I?
A mailbox.
A boat is floating in the water, and a heavy plank of wood is on the boat. If the plank is thrown overboard into the water, what will happen to the water level?
The water level will drop. When the plank is on the boat, it displaces a volume of water equivalent to the weight of the plank. When it's in the water, it displaces only a volume equal to its own volume, which is less than the volume displaced by its weight.
You have two glasses, one filled with water and the other filled with wine. You take a spoonful of water and pour it into the wine glass, then take a spoonful of the wine-water mixture and pour it back into the water glass. Is there more water in the wine or more wine in the water?
The amounts of water in the wine and wine in the water are the same. The process of mixing and exchanging liquids balances out the quantities.
Four people need to cross a bridge at night. They only have one torch, and the bridge is too dangerous to cross without it. The bridge can only hold two people at a time. The four people take different times to cross: 1 minute, 2 minutes, 7 minutes, and 10 minutes. How do they all get across in the shortest time possible?
1. The 1-minute and 2-minute people cross first with the torch (2 minutes). 2. The 1-minute person goes back with the torch (1 minute). 3. The 7-minute and 10-minute people cross with the torch (10 minutes). 4. The 2-minute person goes back with the torch (2 minutes). 5. The 1-minute and 2-minute people cross again (2 minutes). Total time: 17 minutes.
