Relative frequency is actually another term for proportion. It can be found by dividing the number of times an event occurs by the total number of times the experiment is done. In probability, this is often written in the notation *rfn(E) = r/n,* in which *E* is the event, *n* is the number of times the experiment is repeated, and *r* is the number of times *E* occurs. For example, a symmetrical coin can be tossed 50 times *(n)* in order to find out how many times tails will occur (*E*). If the result is 20 tails (r) and 30 heads, then the equation becomes 20/50, or 2/5 = 0.4; or, the relative frequency is 0.4 for tails. If this experiment is repeated over and over, the relative frequency will eventually get closer and closer to 0.5, which is the true value that should result when tossing a two-sided symmetrical coin.