Question

Calculate the probability of flipping a coin 20 times and getting 4 heads. Round your answer to the nearest ten thousandth?

Answer 1

`0.0046`

Explanation:

I'm going to assume you know binomial probability, with the general form of:

`sum_(k=0)^(n)C_(n,k)(p)^k((~p)^(n-k))`

We're flipping a coin 20 times `(n=20)` and we want 4 heads `(k=4)`. The probability of getting heads on any given roll is `0.5`, therefore `p=0.5`. This means that the probability of not getting heads is also `0.5`, and so `~p=0.5`:

`C_(20,4)(.5)^4((.5)^(16))=4845xx0.0625xx0.00001525878=0.00462055206~~0.0046`