Mudonite

One day Pete, a promising young businessman, recieved a shipment of mugs that he was going to use to promote his company. Upon opening the box, Pete discovered that some of the mugs were faulty. He called in his wives Karen and Julia, and asked them to take a look. "Quite a few of these mugs are broken," he commented to them, "but how many?" Karen looked thoughtful and examined the mugs while Pete and Julia waited patiently. Eventually she turned to them and said "I'd say that 3/8 of these mugs are faulty." Pete nodded slowly and said "But can you show me why?" Karen frowned and said "No, I can't, I'm only a D-grade." At this point Pet