Here are three circles and two squares, inscribed successively as shown.
If the diameter of the largest circle is 10, what is the diameter of the smallest circle?
Here are three circles and two squares, inscribed successively as shown.
If the diameter of the largest circle is 10, what is the diameter of the smallest circle?
Ten senators are about to enter Congress when a barrage of snowballs knocks off their tophats. Each retrieves a hat at random. What is the probability that exactly nine of them receive their own hats?
A puzzle by Angelo Lewis, writing as “Professor Hoffman” in 1893:
A man went into a shop in New York and purchased goods to the amount of 34 cents. When he came to pay, he found that he had only a dollar, a three-cent piece, and a two-cent piece. The tradesman had only a half- and a quarter-dollar. A third man, who chanced to be in the shop, was asked if he could assist, but he proved to have only two dimes, a five-cent piece, a two-cent piece, and a one-cent piece. With this assistance, however, the shopkeeper managed to give change. How did he do it?
From the 2000 Indiana College Mathematics Competition:
Four suspects, one of whom was known to have committed a murder, made the following statements when questioned by police. If only one of them is telling the truth, who did it?
Arby: Becky did it.
Becky: Ducky did it.
Cindy: I didn’t do it.
Ducky: Becky is lying.
Here’s the floor plan of a house with five rooms. Can you draw a continuous line that passes through each of the 16 wall segments once and once only? If it’s possible, show how; if it’s not, explain why.
We have 27 wooden cubes. The first is marked A on every face, the second B, and so on through the alphabet to Z. The 27th cube is blank. Is it possible to assemble these cubes into a 3×3×3 cube with the blank cube at the center, arranging them so that cube A adjoins cube B, cube B adjoins cube C, and so on, forming a connected orthogonal path through the alphabet?