Here is a question someone recently asked me: What’s the probability that two students taking a multiple choice test with 29 questions will get exactly the same wrong answers on 10 of the questions?
My answer? Let’s restate this question to make it a lot simpler. Can we assume they also got the same correct answers? If so, then the question simply becomes, “What’s the probability that 2 students choose the same answer for all 29 questions?”
P(all same) = \((1/4)^{29} = .000000000000000003\)