| 听说你也是学数学的， 做做这个: |
| 送交者: 要饭花子 2008月09月06日19:24:55 于 [诗词歌赋] 发送悄悄话 |
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2 boys who live 14 miles apart start at noon to walk toward each other at rates of 3 mph and 4 mph respectively.
One boy has a dog joining their walking game at rate of 5.5 mph at the same starting time. The dog runs faster than boys walk. Once it meets the other boy, it returns immediately. Then, the dog returns again once it meets the master. So the dog runs back and forth between two boys until two boys meet. Question: how many miles has the dog run when 2 boys meet? |
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