A cuboid swimming pool is 60m long and 30m wide, and the original depth of water in the pool is 1.5m. If a water pump is used to drain the water out, and the water is drained at 2.5m**3 per minute, how many hours will it take to drain the water in the pool?
一个长方体游泳池，长60m，宽30m，池内原有水深1.5m．如果用抽水机向外排水，每分钟排水2.5m**3，需要几小时才能把池内的水排完？
<result>18</result>