There are six glasses in a row. The first three are full of water, and the next three are empty. By moving only one glass how can you make them alternate between full and empty?
You are a cook in a remote area with no clocks or other way of keeping time other than a four-minute and a seven-minute hourglass. On the stove is a pot of boiling water. Jill asks you to cook a nine-minute egg in exactly 9 minutes, and you know she is a perfectionist and can tell if you under cook or overcook the egg by even a few seconds. How can you cook the egg for exactly 9 minutes?
1. Flip both hourglasses over and drop the egg into the water. 2. When the 4-minute timer runs out, flip it over (4 minutes elapsed, 3 remaining on the 7-minute timer). 3. When the 7-minute timer runs out, flip it over. (7 minutes elapsed, 1 remaining in the 4-minute timer) 4. When the 4-minute timer runs out, flip the 7-minute timer over. (8 minutes elapsed. 6 minutes remained in the 7-minute timer, but flipping it over leaves one minute’s worth of sand on top. When it runs out exactly nine minutes will have elapsed.)
An apple. They fall off trees and can be sweet or bitter depending on the type of apple. Most people buy apples, but you can get a free one if you have an apple tree. In olden days apples were used to throw at a person you loved, and in 2013 the company, Apple, pushed past Exxon Mobile to have the largest market capitalization in the United States.
Fred was almost done packing for the day, with five packages left. Unfortunately, Fred dropped the labels and had no idea which label went to which package. What is the probability that Fred managed to correctly label exactly four of the five packages?
Zero. If Fred had correctly labeled four packages, the fifth label would belong to the fifth package and all packages would be correctly labeled. Therefore it is impossible to mislabel exactly four packages.