the three tosses of the coin, so in this case we have parameter n=3 . Furthermore, we were interested in counting the number of heads occurring in the three tosses, so a "success" is getting a heads on a toss, which occurs with probability 0.5 and so parameter p=0.5 . Thus, the random variable X in this example has a binomial (3,0.5) distribution and applying the formula for the binomial pmf given
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