Shipwrecked Saga

Apr 17, 2021

RAY: This is the first in the rising floodwaters series. A family of four and their dog get trapped on an island when rising floodwaters tear out the bridge they used just a few hours before. Frantically they search for some means of crossing back to the mainland and finally when they've just about given up hope, the son says, "I found a small boat and oars." They gather around but their joy is short-lived because the manufacturer's instructions -- printed on the back of the boat -- say that the boat can carry only 180 pounds. Thank God Grandma's not here. It's just Mom, Dad, the two kids, and the dog. And the dog is the only one of them who can swim.  

Well, the father weighs 170. The mother says she weighs 130. The son is 90 pounds. And the daughter is 80. The dog weighs 15 pounds. Everyone can row except the dog, who can swim. And the question is: is there any way the family can be saved? And if so, what are the fewest number of crossings to save everyone?



RAY: Now, the fact that the dog can swim is a red herring. Because the dog doesn't have to swim at all. Here's how it's done. The boy and the girl row over to the mainland.

And that's 170 pounds. One of them comes back. Doesn't matter which one. On the next trip the mother and the dog row to safety.

So now we got one of the kids over there, the mother and the dog. But now the other kid comes back. So the only two that have reached safety so far are the mother and the dog. The boy and the girl row over again. One of them comes back. The father rows over. The other kid comes back to the island and now the two kids row to safety together. And then when they get there, they look for the car.

How many trips was that? It's nine crossings.


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