BRAINTEASERS: THE AFTERMATH
by DON STEINBERG
Issue of 2003-02-03

PROBLEM: In a terrible car accident, a man is killed and his son is rushed to the hospital for surgery. As the boy is wheeled into the operating room, the surgeon looks at the patient and says, "I cannot operate on this child. He is my son." How is this possible?

ANSWER: The surgeon is the boy's mother.

SUBSEQUENTLY: Interns plead with the female surgeon, saying that her stubbornness about operating on the boy is jeopardizing his health, yet she steadfastly refuses. It is decided that the boy's broken foot must wait until another surgeon is summoned. Suddenly, the door bursts open—it is the boy's father, alive. "Just do the surgery, Elaine!" he shouts.

"Hey," she replies, "do I come to your job and tell you how to drive?"

PROBLEM: A king wants to hire a royal adviser, so he invites his kingdom's three wisest men to engage in a contest of wits. He sits them down facing one another and walks behind them, putting a cap on each man's head. He tells them that he has given each of them a red cap or a white cap; in fact, he has placed red caps on all three heads. No one can see what he himself is wearing; there are no mirrors or other ways to cheat. The king says, "Raise your hand if you see someone wearing a red hat." All three men raise their hands. Then the king says, "All right, now, if you know what color your cap is, stand up."

For several minutes, no one moves. Then wise man No. 3 stands up. "I am wearing a red cap!" he proclaims. How did he know?

ANSWER: Wise man No. 3 first imagined himself wearing a white cap. "If I have a white cap," he reasoned, "then when wise man No. 2 raised his hand he must have been looking at wise man No. 1's red cap. Wise man No. 1, being smart, would have realized immediately that the red cap seen by No. 2 had to be his, and he would have stood up. Wise man No. 2 would have reached the same conclusion and he would have stood up quickly as well. Since neither of the others stood up, I must not be wearing a white cap. I must be wearing a red one."

SUBSEQUENTLY: Wise man No. 3 is made the king's royal adviser. Two days later, the king consults with him. "The people of my kingdom are unhappy," he says. "There is much misery and disease, farmland lies fallow, and war may be imminent. What shall I do?"

The wise man thinks for a moment. Then he says, "Sire, do any of those people happen to be wearing a red hat?"

PROBLEM: I was born in Boston, and my parents were born in Boston. Yet I was not born a United States citizen. How is this possible?

ANSWER: I was born before 1776, before the United States was created.

SUBSEQUENTLY: Like many others, I became a proud U.S. citizen in 1776. The ensuing years have been arduous for me, and I bear no small shame for the unholy means by which I have sustained myself for more than two centuries. You see, I am not only a U.S. citizen . . . I am also a vampire.

PROBLEM: A traveller visits an island inhabited by two types of people, knights and knaves. Knights always tell the truth; knaves always lie. The visitor falls in love with a local girl and wants to marry her. But before marrying he wants to be sure she is not a knave. An island tradition prohibits men from speaking to women until they are married. So the traveller must ask the girl's brother, who may be a knight or a knave and is not necessarily the same type as his sister. The traveller is allowed to ask the brother one question to find out if his potential bride-to-be is a knave. What is the question?

ANSWER: Are you and your sister of the same type? If the brother answers yes, then, no matter whether he is a knight or a knave, his sister must be a knight. If the brother answers no, the sister must be a knave.

SUBSEQUENTLY: The bride's brutal honesty soon sours the marriage, and the visitor leaves the strange island heartbroken, vowing never again to book travel through the Internet. Knights and knaves gradually intermarry, and within three generations everybody on the island lies occasionally, at unpredictable times.