1.) Jolly Jugs Problem
You are standing next to a well, and you have two jugs. One jug has a content of 3 liters and the other one has a content of 5 liters.
Question: How can you get just 4 liters of water using only these two jugs?
2.) Growing Water-Lily Problem
In the middle of a round pool lies a beautiful water-lily. The water-lily doubles in size every day. After exactly 20 days the complete pool will be covered by the lily.
Question: After how many days will half of the pool be covered by the water-lily?
3.) The Wolf, the Goat, and the Cabbage Problem
A man has a wolf, a goat, and a cabbage. He must cross a river with the two animals and the cabbage. There is a small rowing-boat, in which he can take only one thing with him at a time. If, however, the wolf and the goat are left alone, the wolf will eat the goat. If the goat and the cabbage are left alone, the goat will eat the cabbage.
Question: How can the man get across the river with the two animals and the cabbage?
4.) Happy Handshaking Problem
Jack and his wife went to a party where four other married couples were present. Every person shook hands with everyone he or she was not acquainted with. When the handshaking was over, Jack asked everyone, including his own wife, how many hands they shook. To his surprise, Jack got nine different answers.
Question: How many hands did Jack’s wife shake?
5.) The Round Table Problem
Yesterday evening, Helen and her husband invited their neighbours (two couples) for a dinner at home. The six of them sat at a round table. Helen tells you the following: “Victor sat on the left of the woman who sat on the left of the man who sat on the left of Anna. Esther sat on the left of the man who sat on the left of the woman who sat on the left of the man who sat on the left of the woman who sat on the left of my husband. Jim sat on the left of the woman who sat on the left of Roger. I did not sit beside my husband.”
Question: What is the name of Helen’s husband?