The result of an exam score for a given class is normally distributed. If the mean score is 85 points and the standard deviation is equal to 20 points, find the cutoff passing grade such that 83.4% of those taking the test will pass.
Assume that a bank knows from past experience that between 10 and 11 a.m. of each day, the mean arrival rate is 60 customers per hour. Suppose that the bank wants to determine the probability that exactly two customers will arrive in a given minute time minute interval between 10 and 11 a.m. Arrivals are assumed to be constant over a given time interval. Calculate the probability.