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标题: [求助]一道PREP上的题,不知答案为何选它~~ [打印本页]

作者: Vigiela 时间: 2009-10-18 17:03
标题: [求助]一道PREP上的题,不知答案为何选它~~

A circular jogging track forms the edge of a circular lack that has a diameter of 2 miles. Johanna walked once around the track at the average rate of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the folowing is a correct statement?

正确答案：2.0<t<2.5

我的解题思路：2pai*1=3t，

但解出来不对啊~~我不知错哪了，恳请高人帮帮忙~~万分感谢！！！！！

作者: biglin1987 时间: 2009-10-18 17:20
楼主解得没错，t=2pi/3，这个数就是2.0<t<2.5的

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