Gogoma, Inc., has a two-stage production line. The first stage makes an engine and the second stage does the drone assembly. The engine stage has 30 parallel stations and the drone assembly consists 10 parallel stations. Because all engines are the same, the time for a station to build an engine is exactly 20 minutes. However, the drone customization processes make the drone assembly more difficult. Statistically, it takes 25 minutes on average to complete a drone assembly. To manage the inventory on engines, a Kanban system is utilized. In other words, the engine station cannot start to build a new engine until receiving a Kanban card. In the production system at Gogoma, there are m cards available (e.g., maximum inventory of engines is m). If Gogoma wants to be sure that the probability of a drone station finding an engine in stock is at least 95%, how large should m be?