From a research paper, it is known that the number of soldiers who died annually by being kicked by a horse followed a Poisson distribution with an average of 0.61 death in an army corps each year.
(a) Find the standard deviation of death in an army corps each year.
(b) Find the probability of exactly 3 deaths in an army corps in a given year.
(c) Find the probability of at most 2 deaths in an army corps over an 8-year period.