Tighten two ropes between corners of a square. Put one ring on each rope and tighten another rope between them. That rope goes through the ring on sheep’s neck.

The smaller wheel turns around 4 times.

Imagine the two wheels turning next to each other. While bigger wheel turns once (24 teeth) small one turns three times (3 x 8 teeth) to the other side.

Now we want the big wheel to stop and the small wheel to turn around the big one. There it makes one additional turn on the way around the big wheel. If you can’t imagine that you can try with two coins. If you hold one and roll the other around the first one it doesn’t turn once but two times.

Still didn’t get it? Disassemble some clockwork and try it.

In 15 minutes. After five minutes you take one steak off and turn the other. After 10 minutes one steak is ready and the other two need to be finished from second side.

Man said: “You will neither leave nor hang yourself”

Mother-in-law can’t just leave. The man would be lying and she promised to stay if he lies.

She can stay only if man lied it means that mother-in-law has to either leave or hang herself. She can’t stay and leave at the same time. So only thing she has left to do is hang herself.

You just have to tell mother in law the opposite of what you want…

Best is to shoot in the air.

If you shoot Bill and hit by chance you are surely dead.

If you shoot on Kid and hit there is a 50% chance you die before you have a chance to shoot on Bill.

If you shoot into the air Bill will shoot on Kid (he knows he is a better shooter) if he misses Bill is dead if he hits Kid dies and now you can shoot and you have 1/3 chance to win.

If you hit any of your opponents you are always in a worse situation.

“It’s certain that you will hang me”

If the judge decides you were right he should shoot you. But you would have lied in that case.

And if he decides you lied he should hang you but it would mean you told the truth.

Friend told me about another solution (probably easier but not that nice :))

If you just say: “I’m lying right now” the judge probably won’t be able to solve it either…

Cannibal and missionary there (or two cannibals). Missionary back (cannibal).

Two cannibals there one back.

Two missionaries there. Missionary and cannibal back.

Two missionaries there.

Now three missionaries and a cannibal moved to the other bank. The cannibal can now travel his friends one by one.

I’m looking at two laughing black Chinese. If I was dirty they must realize that they’re dirty. They would both see that I’m clean so they’re laughing at each other. If they didn’t realize this and are still laughing it has to mean that I’m dirty too.

I hope the picture is quite illustrating.

Another solutions exist this seems most elegant to me though. If you have a different one you can easily check if it is correct yourself.

Turn on the first switch and wait for a while. Turn off the first one and turn on the second. Go into the room. One bulb is shining, the second bulb is hot and the third one nothing…