There are 100 young pioneers on the shore preparing to take a boat to Island A, which is 600 meters away from the shore in the lake. After the last person arrives at Island A for 15 minutes, they will go to Island B, which is 900 meters away from Island A. There are motor boats and wooden boats. 1, the engine boat and the wooden boat travel 300 meters and 150 meters per minute respectively, and the engine boat and the wooden boat can seat 10 people and 25 people respectively. How long will it take the last group of young pioneers to arrive at Island B? (calculated by the hour)
有100名少先队员在岸边准备坐船去湖中离岸边600米的甲岛，等最后一人到达甲岛15分钟后，再去离甲岛900米的乙岛，现有机船和木船各1条，机船和木船每分钟各行300米和150米，而机船和木船可各坐10人和25人，问最后一批少先队员到达乙岛，最短需要多长时间？(按小时计算)
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