Question

If a fair coin is tossed 8 times, what is the probability, to the nearest thousandth, of getting exactly 2 tails?

Answer 1

0.109

Explanation:

Probability is expressed by the number of desirable outcomes over the total outcomes. The total outcomes would be 2^8 because there are two possibilities in each flip, and using the fundamental counting principle, you get 2^8 total outcomes. Next, to find the amount of situations where you only flip two tails, you use 8 choose 2 because we are looking for the amount of ways you can choose 2 out of the 8 to be tails. 8 choose 2 is the same as:

8! / (6! x 2!) - 28

So, the probability is:

28 / 2^8 or 28/256

As a decimal, this is: 0.109375

And rounded to the nearest thousandth it's 0.109