Tomoko Arakawa, a clerk at the Department of Motor Vehicles, processes customers at an average rate of 6 per hour (λ = 6 customers per hour). Assume all the Poisson conditions regarding independence, etc., are met. How likely is it that a randomly selected customer will take?
a. At least 15 minutes (1/4 hour) to process?
b. No more than 20 minutes (1/3 hour) to process?
c. Between 10 and 15 minutes to process?