The rate at which customers are served at an airport check-in counter is a poisson process with a with a rate of 9.5 per hour. suppose that a random sample of 50 customers is observed. the probability that the average waiting for these 50 customers is less than 8 minutes is given by, p(latex: \overline{x}x ¯ < 8) = p(z < a), where z is the standard normal variable. what is the value of a? report your answer in 3 decimal places.