Consider a computer outlet store with only one employee. All customers wait in a queue until they are served by the employee. The average time between two customer arrivals equals 0.9 minutes (Poisson arrival process). On average the employee can help 81 customers per hour (negative exponentially distributed service times). What is the probability that there are 4 customers or less at the computer outlet store (waiting plus being served)? Express the probability as a number between 0 and 1. (Round your answer to two decimals)