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Suppose I roll a 20 sided die 5 times, what is the probability that it will land on 20 exactly 2 times, 3 times, and 4 times?
2 Answers
- ?Lv 74 years ago
This is a binomial probability with p=1/20, q=1-p=19/20 and n=5.
P(X=k)=C(n,k)p^k q^(n-k)
I leave the evaluation of the formula up to you for k in {2,3,4}.
- 4 years ago
I understand the probability for it to land on 20, 5 times in a row is 1 : 3.2million. But I'm not sure how to factor in extra dice rolls. If I only needed to get 20, 2 times but i have 5 attempts to get it, what are the odds that i succeed in my attempt?