Comment by meindnoch
4 years ago
Conditional probability doesn’t work like that.
If you always have a bomb with you, then the probability of you sitting on a plane with a bomb is 1, and thus the probability of you sitting on a plane with another bomb is again 10^-4.
Yes, the post you’re replying to was recounting a joke :)
Indeed. Hmm, but what if I roll a D20 before each flight and take a bomb only if I get a "1"? Do I decrease the average two-bombs probability to 5·10⁻⁶?
Yes. But the conditional probability of the plane having a bomb that’s not yours will still be 10^-4.