Suppose a person is forced to play the Russian Roulette. Here is how it works: the person must try two, each time spinning a six-chambered revolver before pulling the trigger. He also gets two options to choose from:
- A revolver with two bullets in it
- Randomly select one of the two revolvers – one carrying three bullets and the other with one bullet.
Which is a better choice?
Let’s evaluate the survival chance of each:
1. Revolver with two bullets firing two times:
Probability survival after two rounds (randomised and made independent by spinning the barrel each time) = (4/6)x(4/6) = 0.44
2a. Revolver with three bullets:
(3/6)x(3/6) = 0.25
2b. Revolver with one bullet:
0.69
The chance of 2a or 2b to occur is 50:50. Therefore, the overall probability in the second case is (1/2) x (0.25 + 0.69) = 0.47
well, the second option gives a slightly better chance of survival!
