A carwash has two machines: machine A and machine B. Machine A cleans better, so machine B is only used when machine A is already occupied. Cars will line up if both machines are occupied. 4 cars arrive at the carwash every hour, and each machine is able to process 5 cars an hour.

i) What percent of the time are both machines occupied?

ii) What percent of the time is machine A occupied?

ii) What percent of the time is machine B occupied? iv) How many cars does each machine need to process for the carwash to be idle at least 80% of the time?