关于数学机经第一题和第429题

kaneroy

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~~~

kaneroy

。。。。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~~~~

shiningsmile

同问啊，也这么理解的！大牛来指教啊！

kaneroy

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 ?