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JDCRex: Let's say there's an outcome that is 2.5% likely to occur per event. To get the expected number of times this would fire over 50 events, is it just as simple as 50 x 2.5% i.e. 1.25 times?


The probability mass distribution for the number of times this outcome will be observed is binomial, with parameters 50 and 0.025. In other words the probability of observing k instances of this outcome in 50 events is

(50!/(k!(50-k)!)) (0.025)^k (0.975)^(50-k)

The mean (expected value) of this distribution is (50)(0.025) = 1.25.

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