U2 has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge. You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them.
The flashlight must be walked back and forth. It cannot be thrown and other tricks like that are not needed to solve the problem. The solution is simply a matter of allocating resources in a certain order. Each band member walks at a different speed. A pair must walk together at the rate of the slower man’s pace:
Bono: 1 minute to cross
Edge: 2 minutes to cross
Adam: 5 minutes to cross
Larry: 10 minutes to cross
For example: if Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission.
This is one of my favorite brain teasers and I want to give you the satisfaction of figuring it out on your own. If you’re having a hard time, here’s a hint: There is a valid answer that doesn’t require tricks like throwing the flashlight or shining it backwards or having some other means of moving the flashlight.
There’s an assumption people often make that keeps them from solving this. Two members cross the bridge each time, but neither one of the two who crossed necessarily need to return. Think about how that would be possible. If you’re still stuck, use objects to simulate their movements. Use whatever you have laying around – pens, paper, erasers – and move them back and forth. Good luck!
Snow. Every kid has taken a bite of snow, but thousands of people die every year in snowstorms. Watch out for photokeratitis, otherwise known as snow blindness. And if you’re exposed to snow for too long, you can lose limbs to frostbite. Just an inch or two of snow makes them treacherous.
A recent snowfall makes the world white, and kids love to build snowmen, snow forts and have snowball fights. Some people live in igloos, built out of snow.
The executor went to the neighbouring farm and asked to borrow a sheep for a few minutes. Then he returned to the sons and said, “Half of the (now) twenty sheep is 10. A quarter of the twenty sheep is 5. A fifth of the twenty sheep is 4. 10 + 5 + 4 = 19. Then the executor took the borrowed 20th sheep back to the neighbour.
They are the only letters in the alphabet that are not found at the beginning of the name of a state in the United States of America. The rest of the letters in the alphabet, namely ACDFGHIKLMNOPRSTUVW, start the name of at least one state. Incidentally, eight different states each start with the letters M and N, tying them for the most states starting with a particular letter. The next highest is a three-way tie between A, I and W with four each.
She will always need to give you 5 apples. You both need at least 5 apples to begin with, but apart from that it doesn’t matter exactly how many you each have. When she gives you 5 you will have 10 more than her because she will lose 5 and you will gain 5, resulting in a net difference of 10.
For example, if you each have 25 apples and she gives you 5 of hers, she will be left with 20 and you will now have 30, precisely 10 more than she has.
I hide in the daylight but prefer the sun,
I have no fingers but can hold a gun,
I have three eyes but cannot see,
I live on land but in a tree,
I’m spotted in pink and cannot grow,
When you look away is when I show.
I come in the form of a question. If you don’t know the answers, you will think a lot, but when you know or you are being told the answer it sounds simple that you will think everybody can easily know.