Q : You are tied to your chair and can't get up.Here's a gun. Here's the barrel of the gun, six chambers, all empty. Now watch me as I put two bullets in the gun. See how I put them in two adjacent chambers? I close the barrel and spin it. I put the gun to your head and pull the trigger. Click. You're still alive. Lucky you! I'm going to pull the trigger one more time. Which would you prefer, that I spin the barrel first, or that I just pull the trigger?
A:There are two bullets in six chambers, or, to put it more optimistically, four empty chambers out of six. Spin
the barrel, and you've got a four-in-six, or two-in-three, chance of survival.For the other option, look at it this way. The four empty chambers are all contiguous. One of them just spared your life. For three of these four empty chambers, the "next" chamber in succession will also be empty. The remaining empty chamber is right before one of the two bullets. That means you have a three-in-four chance of survival when you don't spin.
Three-fourths is better than two-thirds, so you definitely don't want the barrel spun again.
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