statistics - Random variable and trying to find $E(N)$ - Mathematics

Statistics - Random variable and trying to find $E(N)$ - Mathematics

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3/27/13 statistics - Random variable and trying to find $E(N)$ - Mathematics math.stackexchange.com/questions/343975/random-variable-and-trying-to-find-en 1/2 Random variable and trying to find E ( N ) Given N = random variable that counts the fraction of trials that are successful trials = 12 N = S /12 S = number of successful trials E ( N ) =? i don't know how to find is there a specific formula? can someone help me out with this problem E ( N ) (statistics) (discrete­mathematics) edited 1 hour ago azimut 4,015 1 9 31 asked 1 hour ago jyuserersh 70 4 1 You can calculate the probability of a single experiment succeeding, right? Call that , as it's the same for every other experiment. So imagine each experiment as a whole being a single coin flip with probability of success p . So you're looking for the expected number of successes after 12 flips. Do you know which distribution this follows? p Alex 1 hour ago 1 Answer It is useful to introduce some notation. Define random variables by if the -th trial is successful, and if the trial is not successful. , , Q , X 1 X 2 X n = 1 X k k = 0 X k Then : the sum of the $X_i% counts the number of successful trials.
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