Aug 22, 2005
RAY: A family of four and their dog are trapped on an island, when rising floodwaters tear out the bridge that they had used just a few hours earlier.
When they had just given up hope the son says, "I've got a small boat and oars."
But their joy was short-lived. The manufacturer's instructions printed on the boat stern say that the boat can carry only 180 pounds.
The dog is the only one who can swim.
The father weighs 170. The mother says she weighs 130 but it's more like 155. The son is 90 pounds, the daughter is 80, and the dog is 15.
TOM: The dog is going to have to take the boat back to the port!
RAY: Here's the question: Is there any way that the family can be saved?
TOM: We know that they can be saved! We would never give a puzzler that didn't have a happy ending.
RAY: Right. So, what's the fewest number of crossings they have to make to save everybody?
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When they had just given up hope the son says, "I've got a small boat and oars."
But their joy was short-lived. The manufacturer's instructions printed on the boat stern say that the boat can carry only 180 pounds.
The dog is the only one who can swim.
The father weighs 170. The mother says she weighs 130 but it's more like 155. The son is 90 pounds, the daughter is 80, and the dog is 15.
TOM: The dog is going to have to take the boat back to the port!
RAY: Here's the question: Is there any way that the family can be saved?
TOM: We know that they can be saved! We would never give a puzzler that didn't have a happy ending.
RAY: Right. So, what's the fewest number of crossings they have to make to save everybody?
Think you know?
Drop us a note via
http://www.cartalk.com/email/email.html
Answer:
RAY: 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.
TOM: And that's 170 pounds.
RAY: Right. One of them comes back. It doesn't matter which one. The next trip, the mother and the dog row to safety.
TOM: Got it. So now we've got one of the kids over there, the mother and the dog.
RAY: 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.
TOM: How many trips was that?
RAY: It's nine crossings. So who's our winner?
TOM: The winner is Jack Mueller from Dickson, California.
Here's how it's done.
The boy and the girl row over to the mainland.
TOM: And that's 170 pounds.
RAY: Right. One of them comes back. It doesn't matter which one. The next trip, the mother and the dog row to safety.
TOM: Got it. So now we've got one of the kids over there, the mother and the dog.
RAY: 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.
TOM: How many trips was that?
RAY: It's nine crossings. So who's our winner?
TOM: The winner is Jack Mueller from Dickson, California.
