Bullet Proof

In the early years of World War II, fighter planes would come back from battle with bullet holes. The Allies noticed the areas that were most commonly hit by enemy fire. They sought to strengthen the most commonly damaged parts of the planes to reduce the number that were shot down. A mathematician, Abraham Wald, pointed out that perhaps there was another way to look at the data. Perhaps the reason certain areas of the planes weren't covered in bullet holes was that planes that were shot in those areas did not return. This insight led to the armor being reinforced on the parts of the plane where there were no bullet holes.

Riddle of the Sands

A man rode up to the US border on his motorcycle with two large bags on his shoulders. The border guard stopped him and asked, “What's in the bags?” The man replied that the bags were full of sand, but the guard didn't believe him. The guard detained the man and ripped open the bags which revealed nothing but sand. He even had the sand analyzed, only to find that it really was just sand. Two days later, the same thing happened. And then it happened again, two days after that. Every time, the guy on the motorcycle had nothing but sand. This went on for years. It drove the border guard crazy and he eventually lost his job. One day, he tracked down the man and said to him: “I’m no longer a border guard, but I have to know. What were you smuggling? Because I know you were smuggling something.” The man smiled at him and said: “Motorcycles!”