In one of the archaeological excavation sites, the artifact density (number of prehistoric artifacts per 10 liters of sediment) was 1.0. Suppose you are going to dig up and examine 50 liters of sediment at this site. Let r = 0, 1, 2, 3,... be a random variable that represents the number of prehistoric artifacts found in your 50 liters of sediment. Compute the probability that in your 50 liters of sediment you will find 3 prehistoric artifacts. Round your answer to the nearest ten thousandth.