Calculate the probability that in four tosses of a fair coin, there are at most three heads.

There are a total of \(2^4 = 16\) possible outcomes. Only one of those has more than 3 heads, namely 4 heads. So we need to subtract it from the total number of outcomes and get the final probability of \(\frac{2^4-1}{2^4} = \frac{15}{16}\).