Identifying n, p, and x
For each situation, identify the sample size n, the probability of success p, and the number of successes x. When asked for the probability, state the answer in the form b(n, p, x).
There is no need to give the numerical value of the probability. Assume the conditions for a binomial experiment are satisfied.
a. According to the Federal Highway Research Institute in Germany, 2 out of 3 persons in an accident get killed. In a random sample of 27 persons meeting with an accident, what is the probability that exactly 12 persons would have died?
b. Twenty-five percent of the persons killed in accidents are pedestrians. If we randomly select 27 persons who have died in an accident, what is the probability that 12 persons are pedestrians?