问道数学题 prep ps2 110

tonyt913 · 发表于 2011-11-28 11:14:31

110. 11325-!-item-!-187;#058&008034
During a trip on an expressway, Don drove a total of x miles. His average speed on a certain 5-mile section of the expressway was 30 miles per hour, and his average speed for the remainder of the trip was 60 miles per hour. His travel time for the x-mile trip was what percent greater than it would have been if he had traveled at a constant rate of 60 miles per hour for the entire trip?

谢谢nn们~~

dliu64 · 发表于 2011-11-28 12:44:06

这个题的答案答案是 1/12 么？？

我的解题思路就是看最前面的5mile.. 因为题说and his average speed for the remainder of the trip was 60 miles per hour。也就是说和60匀速跑完全程的速度是一样的。。只有前面的5mile 一个他是用了30 mile，一个他用了60 mile 。所以答案就是 5/60-5/30= -1/12.也就是说多用了1/12小时。

dliu64 · 发表于 2011-11-28 12:44:44

但是感觉这题有点不像我想的这么简单。。。所以。。。错了的话就当我啥也没说啊！！

tonyt913 · 发表于 2011-11-28 12:52:39

多多少时间我倒是算出来了，只是题目让我算percentage，我就糊涂了，感觉要用x来比，但是最后x消不掉

dliu64 · 发表于 2011-11-28 13:32:05

不是你给个答案啊。。答案是多少%

tonyt913 · 发表于 2011-11-28 13:41:52

Prep没破解出来，上面没答案。。。。

问道数学题 prep ps2 110

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