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标题: 关于数学机经第一题和第429题 [打印本页]

作者: kaneroy    时间: 2012-6-19 07:02     标题: 关于数学机经第一题和第429题

429题中有个constant speed,意思是指的恒速么,如果是的话,那前20miles或后20miles的speed是不是就是全程30miles的average speed?
这样的话,条件一二都可以单独推出,就是选D了?求nn解答,谢~~~
作者: kaneroy    时间: 2012-6-19 07:03

。。。。忘了帖题了
第429题
DS说有个人开车都以constant speed, 问他开30miles的average speed是多少
1)开前20miles的speed是某个数值;
2)开last 20miles的speed是某个数值;
求解答~~~~
作者: shiningsmile    时间: 2012-6-19 21:23

同问啊,也这么理解的!大牛来指教啊!
作者: kaneroy    时间: 2012-6-22 08:16

从og上找的一道有关constant speed的题,看来constant speed应该是指一个恒速,至于是全程恒速还是前20miles恒速就要看题目了,继续求大牛指导~~
Car A is 20 miles behind Car B, which is traveling in
the same direction along the same route as Car A.
Car A is traveling at a constant speed of 58 miles
per hour and Car B is traveling at a constant speed
of 50 miles per hour. How many hours will it take for
Car A to overtake and drive 8 miles ahead of Car B ?




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