Cats, Dogs, And Houses
Riddle: Irene and her friend Mark were walking down the street when they saw two houses. Mark wanted to play a game with Irene. He said, "One family lives in each house. And each family has two pets: either dogs or cats. The first family has a dog who likes dry food, while the other pet likes canned food. The second family has a 6-year-old dog and a newborn pet. If you can guess which family has a cat, I'll take you out for lunch." Irene manages to get the riddle right, and the two of them go out for lunch. Which family did she choose?
Answer: Irene chose the first family. There are three different possibilities for the pets that the first family has: 1) an older dog and a younger cat; 2) a younger dog, and an older cat, and; 3) two dogs. Two of these options involve a cat, and all of them are equally possible, so the chance of the first family having a cat is 2/3. There are two different possibilities for the pets that the second family has: 1) a 6-year-old dog and a newborn dog, and; 2) a 6-year-old dog and a newborn cat. One of these options involves a cat, and both of them are equally possible, so the chance of the second family having a cat is 1/2. Irene's odds of winning will be higher if she chooses the first family.
Source: https://www.riddles.com/index.php/11323
