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星期天,洛洛全家人出去游玩,由于玩得太高兴了,忘记了回家的时间。他们慌慌张张地来到一条小河边,河上有座桥,一次只允许两个人通过。如果他们一个一个过桥的话,洛洛需要15秒,妹妹需要20秒,爸爸需要8秒,妈妈需要10秒,奶奶需要23秒。如果他们两个人一块过桥的话,只能按走路慢的人的速度来走。过桥后他们还要走2分钟的路。洛洛一家人急着要到对面去赶最后一班回家的公交车。现在他们只有3分钟的时间,请问:洛洛一家人能否赶上最后一班公交车?他们该怎样过桥?过桥总计用了多长时间?
On Sunday, Lolo’s family went out for fun, forgetting the time to go home because they were so happy. They hurried to a small river with a bridge over the river, allowing only two people at a time. If they cross the bridge one by one, Lolo takes 15 seconds, sister needs 20 seconds, Dad needs 8 seconds, Mom needs 10 seconds, Grandma needs 23 seconds. If they cross the bridge with two people, they can only walk at a slower pace. They also have to walk two minutes after crossing the bridge. Lollo family rush to go across the last bus to go home. Now they have only 3 minutes, I ask: Lorlo family can catch the last bus? How should they cross the bridge? Bridge total spent a long time?