The Hadley Motor Company is located in Florida but has a number of customers in the Pacific Northwest.Sales to those customers are $30 million a year paid in checks that average about $1,500.The checks take an average of nine days to clear into Hadley's Florida bank.A bank in Oregon will operate a lock box system for Hadley for $8,000 a year plus $.50 per check.The system can be expected to reduce the clearing time to six days.

a. Is the lock box system worthwhile if Hadley borrows at 13.5%?

b. What is the minimum number of days of float time the system has to save (to the nearest tenth of a day) to make it worthwhile?