Q&A: Chances and Probability
Chances and Probability
Question
With God’s help,
Hello Rabbi,
The following question came up among the students in our yeshiva in connection with the topic of “majority and fixed status.” The example is of ten airplanes currently parked on the ground, nine of them red and one white, and the question is whether there is a greater chance that specifically a red airplane will crash. Of course, the answer is fifty-fifty. But on the other hand, if we hear that one of the airplanes crashed, then almost automatically we assume that it presumably came from the red group. Why is that, and what changed between the cases?
Many thanks.
Answer
I didn’t understand the question. What is the probability that any airplane will crash while they are on the ground? I didn’t understand what the first of the two cases is supposed to be, the one for which the answer is 50-50.
Discussion on Answer
If you know that one of them will crash when they are in the air, then I don’t see any difference between that and the second case. The probability is not 50-50. Of course, if there is also some mechanical difference between the two groups of airplanes and you are uncertain which mechanical design is better, that is something else.
In short, the issue here is not properly defined. Think it over again and see whether you still have a question.
With God’s help,
What I mean is under the assumption that I know for certain that one of the airplanes will crash when they are in the air.