Counting down to a birthday: The Wknd Puzzle with Dilip D’Souza

A famous story about the great logician Raymond Smallyan (1919-2017) comes from the time someone introduced him as “unique”. Smallyan interrupted: “I’m sorry sir, but I’m the only person in the universe who isn’t unique.”

Smallyan is one of the great minds of our time. His book, A Mixed Bag, tells another favorite story of a class he taught at Princeton. He introduced the students to the famous birthday “paradox,” which isn’t really a paradox, as it goes:

Suppose you are at a party with about 23 people. The timing of the trick can’t fail to cause gasps if it works, and it’s more than likely going to work. Take a bet that at least two people in the party have the same birthday. In fact, you are more likely to win. (Try it, and it’s an interesting puzzle that works math.)

At Princeton, there were only 19 students in his class, so Smallian didn’t try the trick. “There’s a small chance,” he said sadly, “that you both have the same birthday.”

But someone in the class piped up: “Wait! I’m willing to bet that two people in this class share a birthday.

“I see what you’re up to, dude!” Smalyan said. “You get to know someone else’s birthday in class and it’s the same as yours.”

The student replied: “No! Besides me, I don’t know anyone’s birthday here, I swear.

Smulyan persuaded. Convinced he had the best chance of winning, he took the student’s bet. But Smalyan lost. Why?

Scroll down for the answer.

.

.

.

.

.

.

.

.

.

.

.

Answer:

Unknown or unbeknownst to Smullan, there was a pair of twins in the classroom.

Enjoy unlimited digital access with HT Premium

Subscribe now to continue reading

Freemium

Leave a Comment