One mechanic services 4 drilling machines for a steel plate manufacturer. Machines break down on an average of once every 6 working days, and breakdowns tend to follow a Poisson distribution. The mechanic can handle an average of two repair jobs per day. Repairs follow a negative exponential distribution. a) On the average, how many machines are waiting for service? The average number of machines waiting for service is 0.17 . (Round your response to three decimal places.) b) On the average, what is the waiting time to be serviced? The average waiting time to be serviced is days. (Round your response to two decimal places.)