Of the 1.0 million persons of voting age in Maine, 72% voted in the 2008 presidential election.

Question:

Of the 1.0 million persons of voting age in Maine, 72% voted in the 2008 presidential election. For a randomly selected group of 30 Maine residents who were of voting age at that time, what is the probability that at least 20 of these persons voted in the presidential election?