Using this formula, which I'm confused on using (every practice question I attempted, I got wrong)

Then part B asks On average, how many copy machines are being repaired or waiting to be repaired?

The College of Business and Public Administration at Benton University has a copy machine on each floor for faculty use. Heavy use of the five copy machines causes frequent failures. Maintenance records show that a machine fails every 2.5 days (or =0.4 failure/day). The college has a maintenance contract with the authorized dealer of the copy machines. Because the copy machines fail so frequently, the dealer has assigned one person to the college to repair them. The person can repair an average of 2.4 machines per day. Using the finite-source model, answer the following questions: a. What is the average utilization of the maintenance person? = (Enter your response rounded to four decimal places. ) =1P0=1[n=0N(Nn)!N!()n]1