A shopkeeper says she has two new beagle puppies to show you, but she doesn’t know whether they’re male, female, or a pair. You tell her that you want only a male, and she telephones the fellow who’s giving them a bath. “Is at least one a male?” she asks him. “Yes!” she informs you with a smile. Now we know you can have a male puppy, but what is the probability that the other one is a male?