In analyzing hits by certain bombs in a war, an area was partitioned into 579 regions, each with an area of 0.55 km². A total of 535 bombs hit the combined area of 579 regions. Assume that we want to find the probability that a randomly selected region had exactly four hits. In applying the Poisson probability distribution formula, P(x) = (μ^x * e^(-μ)) / x!, identify the values of μ, x, and e. Also, briefly describe what each of those symbols represents.