Another puzzle by Boris Kordemsky: Jack London tells of racing from Skagway, Alaska, to a camp where a friend lay dying. London drove a sled pulled by five huskies, which pulled the sled at full speed for 24 hours. But then two dogs ran off with a pack of wolves. Left with three dogs and slowed down proportionally, London reached the camp 48 hours later than he had planned. If the two lost huskies had remained in harness for 50 more miles, he would have been only 24 hours late. How far is the camp from Skagway?
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London would have reached the camp one day sooner if he’d covered 50 more miles at full speed. That means he’d have reached it two days sooner, and arrived on time, if he’d covered 100 miles at that speed. So at the end of the first day, 100 miles remained to reach the camp. He covered this in two days with three dogs, so with five dogs he would have covered 5/3(100) = 166 2/3 miles, going 66 2/3 miles beyond the camp in two days. That means a full team of five dogs covers 33 1/3 miles per day. London covered 33 1/3 miles on the first day and 100 miles after that, for a total of 133 1/3 miles.
08/30/2013 Wait, I screwed this up. It’s not correct to say that London covered 100 miles in two days with three dogs; I should have said instead that a full team would have covered 166 2/3 miles rather than 100, and that forgoing the extra 66 2/3 miles would have saved 48 hours, giving a full speed of 33 1/3 miles per day. So the answer was correct, but the solution was wrong. Sorry about that.
(Thanks, Nick and Ben.)
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