Question
"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?"
*Russian roulette is a potentially lethal game of chance in which participants place a single round in a revolver, spin the cylinder, place the muzzle against their head and pull the trigger
Comment:
Despite the long story this is quite simple and quite common probablity question
Interviewed for position: Program Manager, SDE, Test, Analyst
"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?"
*Russian roulette is a potentially lethal game of chance in which participants place a single round in a revolver, spin the cylinder, place the muzzle against their head and pull the trigger
Comment:
Despite the long story this is quite simple and quite common probablity question
Interviewed for position: Program Manager, SDE, Test, Analyst
BBEEEE
EBBEEE
EEBBEE
EEEBBE
BEEEEB
(B-bullet, E-empty)
So, on first try the probability of not get a shot was 3 out of 5 = 0.6. If we don't spin, the remaining choices are:
E->BBEEE
E->EBBEE
E->EEBBE
Which give us 2 of 3 = 0.666, which is better than 0.6