The uptime efficiency of a 20 station automated production line is only 40%. The ideal cycle time is 48 sec, and the average downtime per line stop occurrence is 3.0 min. Assume the frequency of breakdowns for all stations is equal (pi = p for all stations) and that the downtime is constant. To improve uptime efficiency, it is proposed to install a storage buffer with a 15-part capacity for $14,000. The present production cost is $4.00 per unit, ignoring material and tooling costs. How many units would have to be produced in order for the $14,000 investment to pay for itself?