Chances of someone getting caught torrenting one time?

Let’s say someone downloaded a week old movie torrent and that was the first and only torrent they have ever downloaded. What are the chances of there ISP sending them a letter?

Popular: What do these quotes from the movie "Heathers" mean? What was the name of each rocket in october sky movie? Anyone know a good website to watch free Disney movies? Need a creative answer :P? If the Illuminati is/isn't real, why is there references to them in movies, music . cartoons. etc?
More: If you suddenly had control over what kind of movies Hollywood put out, what would you change? I just bought a region 2 dvd player, what are some good dvds only available for region 2? On San Andreas why did the rock take his wife back after she had sex with another man? What happen to peter pan's shadow after he caught it in the darling house? Do deaf people enjoy watching movies?