The Book

A woman walked up to a man behind a counter and handed him a book.

He looked at it and said, “That will be four dollars.”

She paid the man and then walked out without the book. He saw her leave without it but did not call her back.

How come?

Island of Fire

You and your friend have been dropped off by helicopter at the southern end of an island in order to observe an endangered species of bird.

The island is very small. It’s only a hundred yards wide and a thousand yards long. It also has sheer cliffs hundreds of feet high all around it. But finding the rare bird will be difficult because the island is covered in thick brush that’s five feet tall.

Unfortunately, even before you’ve started your search things take a bad turn. You see smoke. As the helicopter took off over the northern end of the island, the pilot flicked out a cigarette butt and inadvertently started a fire that smoldered unobserved for a while and then flared up. It’s now being fanned by a strong wind heading in your direction, and you have no way of contacting the helicopter or calling for help.

The fire will reach you in half an hour. You don’t have any tools with you, so you try to dig a hole with your hands but the ground is too hard. You look over the edge of the cliffs and realize that even climbing down a few feet is impossible, and jumping would mean certain death.

Even from where you’re standing you can tell the heat of the fire is intense. Trying to run through it would be fatal.

So, in order to survive, what do you and your friend do?

Thanks to Everything He Hasn’t Told You Yet by Burton Silver & Martin O’Connor

Wet Logic

True story: There’s a leak under my bathroom sink. I buy a new connector hose. There’s a tag on the middle of the hose that says “1/2 inch COMP to Valve – 1/2 inch FIP to Faucet”. Sure enough, it fits the valve, but it’s the wrong size for the faucet. The end that fits the valve, however, happens to also be the right size for the faucet.

I return to the hardware store looking for a hose that says “1/2 inch COMP to Faucet – 1/2 inch COMP to Valve”.

Unfortunately (or fortunately), they don’t make such a hose.

What was wrong with my reasoning?

Getting Home

There is a man who lives on the top floor of a very tall building.

Everyday he gets the elevator down to the ground floor to leave the building to go to work.

Upon returning from work though, he can only travel half of the distance up riding in the elevator and has to walk the rest of the way up unless it’s raining!

How can this be?

Another System

What’s the opposite of 11?

What’s the reverse of 11?

Overwhelming?

1. Suppose you’re in a hallway lined with 100 closed lockers
2. Begin by opening all 100 lockers.
3. Close every second locker.

4. Go to every third locker and close it if it is open, or open it if it is closed (call this toggling the locker).
5. Continue toggling every nth locker on pass number n.
6. Stop on your hundredth pass of the hallway when you will toggle only locker number 100.

How many lockers are open?

Missing Dollar

Tom, Dick, and Harry each paid 10 dollars for a room at the hotel. When the manager found out, he told the desk clerk that Tom, Dick, and Harry were friends of his and they should be charged only $25.

The desk clerk gave the bell boy $5 and told him to return it to Tom, Dick and Harry. The bell boy, however, decided to give them only three dollars and keep two for himself.

If Tom, Dick and Harry each received $1 back, then that means they only paid $27 for the room. With the $2 the bell boy has in his pocket, the total is $29.

What happened to the missing dollar?

Sensitive!

What’s so special about this pattern?

Water & Wine Glasses

Start with two glasses, one filled with water, the other filled with wine.

A spoonful of wine is taken from the wine-glass and stirred into the water-glass, then a spoonful is taken out of the water-glass and returned to the wine-glass. The operations are repeated.

Is there more water in the wine-glass than there is wine in the water-glass or the other way round?

Black & White Pebbles

Many years ago when a person who owed money could be thrown into jail, a merchant in London had the misfortune to owe a huge sum to a money lender. The money lender, who was old and ugly, fancied the merchant’s beautiful teenage daughter. He proposed a bargain. He said he would cancel the merchant’s debt if he could have the girl instead.

Both the merchant and his daughter were horrified at the proposal. So the cunning money lender proposed that they let Providence decide the matter. He told them that he would put a black pebble and a white pebble into an empty moneybag and then the girl would have to pick out one of the pebbles. If she chose the black pebble she would become his wife and her father’s debt would be cancelled. If she chose the white pebble she would stay with her father and the debt would still be cancelled. But if she refused to pick out a pebble her father would be thrown into jail and she would starve.

Reluctantly the merchant agreed. They were standing on a pebble strewn path in the merchant’s garden as they talked and the moneylender stooped down to pick up the two pebbles. As he picked up the pebbles the girl, sharp eyed with fright, noticed that he picked up two black pebbles and put them into the moneybag. He then asked the girl to pick out the pebble that was to decide her fate and that of her father.

Imagine that you are standing on that path in the merchant’s garden. What would you have done if you had been the unfortunate girl?

-from Lateral Thinking by Edward DeBono