A train leaves New York for Boston. Five minutes later another train leaves Boston for New York, at double the speed. Which train will be closer to New York when they encounter?
If I go halfway to the town (which is 60 km away) at the speed of 30 km/hour, how fast do I have to go for the rest of the way to have the average speed of the entire way 60 km/hour?
These are the conditions in a town:
What is the highest possible number of inhabitants?
- No two inhabitants have the same number of hairs on their head.
- No inhabitant has exactly 518 hairs.
- There are more inhabitants than any inhabitant's hair in the town.
An Arab sheikh tells his two sons to race their camels to a distant city to see who will inherit his fortune. The one whose camel is slower will win. The brothers, after wandering aimlessly for days, ask a wise man for advice. After hearing the advice they jump on the camels and race as fast as they can to the city.
What does the wise man say?
Three masters of logic wanted to find out who was the wisest one. So they invited the grand master, who took them into a dark room and said: "I will paint each one of you a red or a blue dot on your forehead. When you walk out and you see at least one red point, raise your hands. The one who says what colour is the dot on his own forehead first, wins." Then he painted only red dots on every one. When they went out everybody had their hands up and after a while one of them said: "I have a red dot on my head."
How could he be so sure?
Imagine you are in a room with 3 switches. In an adjacent room there are 3 bulbs (all are off at the moment), each switch belongs to one bulb. It is impossible to see from one room to another. How can you find out which switch belongs to which bulb, if you may enter the room with the bulbs only once?Check out the solutions in the puzzle page! :) Sharpening our mind sometimes helps it works better.