2. (12624 The following lists the probability distribution of X, the number of passengers in a sedan going through a ramp. Extend to find the mean and standard deviation of the number of X. X P 0.60 1 0.20 2 0.15 3. (10:24.4) At a grocery store, the number of customers arriving at the checkout line follows Poisson distribution with a rate of 3.6 customers per 3-minute. Find the probability that Note: Write the calculator notation before giving the calculator result. a. At most 4 arrivals in a 3-minute period. c. Any arrival in the next 1-minute period. b. At least 20 arrivals in a 15-minute period