Victor L.

# I'm trying to calculate the probability of winning powerball.

Using conditional probability without replacement I find that the chance of getting 5 white balls (69 uniquely labeled balls in total) correct is 1/1348621560. The problem is when I use binomial coefficients to find the number of possible coefficients I end up with a different probability of 1/11238513. Why do I get 2 different probabilities? I think I got confused somewhere can someone help?

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Tutor
4.8 (33)

Hopkins PhD Student in Statistics

Victor L.

Yes, shortly after posting this I realized that my probabilities were off because of the fact that the tree diagrams were restricting the numbers to a certain order.  The order of the numbers for power ball doesn't matter so I can stick with my binomial coefficient. Thank you for your answer! It definitely gives me confidence in my conclusion.
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11/27/17

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