Anne Teak, the financial manager of a furniture manufacturer, is considering opening a lock-box system. She forecasts that 800 payments a day will be made to lock boxes with an average payment size of $2,000. The bank's charge for operating the lock boxes is $.30 a check. The interest rate is .012% per day.

Daily interest saved: $144

What is the minimum reduction to the time (days) to collect and process each check is needed to justify use of the lock-box system? (Do not round intermediate calculations. Round your answer to 2 decimal places.)