# If a fair coin is flipped 5 times, what is the probability that there will be at least 3 tails?

It is easy to see that these two are mutually exclusive (at least three tails means either exactly 3, 4, or 5 tails, while at least three heads means exactly 0, 1, or 2 tails) and exhaust all possibilities. So, the sum of these two probabilities must equal 1 and thus both, being equal, must individually equal $\frac{1}{2.}$