A swimming pool is 50 meters long, 30 meters wide and 1.8 meters high. The water storage in the pool is 1.2 meters. In summer, the water in the pool needs to be emptied and changed, and the water pump is used to drain the water. The water discharge is 2.5 cubic meters per minute. How many hours will it take to drain it?
一个游泳池，长50米，宽30米，高1.8米．池内蓄水1.2米，夏季到了，要把池内的水排空换水，用水泵向外排水，每分钟排水2.5立方米，需要几小时排完？
<result>12</result>