Suppose you had eight billiard balls. One of them is slightly heavier, but the only way to tell is by put-ting it on a scale against the others. What's the fewest number of times you'd have to use the scale to find the heavier ball?
Answer: The answer is two.
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"Let's play a game of Russian roulette," begins one interview stunt that is going the rounds at Wall Street investment banks. "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! Now, before we discuss your résumé", 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?"
Answer: Don't spin
