Friday, April 16, 2004

Big yellow taxi...or was it black?

A bank robber puts the loot in a suitcase, runs out of the bank, gets into a taxi, and is driven off. A witness sees him. The witness says, "It was a black taxi, not a yellow taxi." Further tests reveal that this witness get's the color of the taxi--whether it is black or yellow--right 80% of the time. So the police dispatcher radios all cars, saying "He's in a taxi. There's an 80% chance it's a black taxi."

Now a supervisor hands the dispatcher a slip of paper that tells the dispatcher that 90% of the taxis in the city are yellow, and only 10% are black. "It's unlikely that the taxi is black," the supervisor says. The dispatcher begins, "Correction..." What should the dispatcher say?