Question

A coin is biased such that the probability of flipping heads is .2. If the coin is tossed 15 times, what is the probability of getting exactly 5 heads?

Answer 1

Since , we are given that we tossed a biased coin and probability of getting heads is 0.2.

Here we see that

1: The number of observations n is fixed. 2: Each observation is independent. 3: Each observation represents one of two outcomes ("success" or "failure"). 4: The probability of "success" p (say) is the same for each outcome.

Thus in this case we use binomial distribution for getting the probability of 5 heads.

Now, we find the probability of getting exactly 5 heads as follows.