Can you write a general formula for the probability that x rats will die in the 8-hour period? Evaluate this formula for x = 0, 1, . . . , 10.

Cancer, Epidemiology
An experiment is designed to test the potency of a drug on 20 rats. Previous animal studies have shown that a 10-mg dose of the drug is lethal 5% of the time within the first 4 hours; of the animals alive at 4 hours, 10% will die in the next 4 hours.