请教一道数学题(钱永强的数学难题精解中的)

At 9:00am a hike was due south of point p. What direction was point Pfrom her position at noon?

(1)From 9 am until 11 am she walked due east at 2 miles per hour, and from 11 am until noon,she walked due north at 3 miles per hour

(2)at noon, she is exactly 4.5 miles from point P

答案是E,但是我觉得是C,可以求出最后在NOON的时候,HIKER离P点的位置(角度数),怎么不行呢??

Another one:

On a recent trip, Cindy drove her car 290 miles, rounded to the nearest 10 miles, and used 12 gallons of gasoline, rounded to the nearest gallon. The actual number of miles per gallon that Cindy's car got on this trip must have been:

(A)290/12.5 and 290/11.5

(B)295/12 and 285/11.5

(C)285/12 and 295/12

(D)285/12.5 and 295/11.5

(E)295/12.5 and 285/11.5

这题怎么解呀?

第一题答案是E，画图理解，题目只给出hike在P正南，但并没有给出P点和hike之间的初始距离，那按照题意就可以算出两种可能，如果距离小于3，那中午是hike在P点的东北方，而距离大于3时，中午hike在P点的东南方。可能解释的有点晕，angichenying画个图想想，牛们可以继续讨论，清晰解答。

第二题290miles，近似到10miles，所以取值范围在285－295之间，12gallons，近似到1gallon，取值在11.5到12.5之间，那求miles per gallon就是最小比最大到最大比最小之间，答案D

谢谢grace.

第一题我明白了.

但是,第二题还不是很明白.首先,D和E有什么区别?其次,如果不近似,就取290,或12,为什么就不行呢?也满足条件呀?

再问一题吧.题目挺长的,要打半天呢,大家帮帮忙,给点回复呀.

The table above shows the cancellation fee schedule that a travel agency uses to determine the fee charged to a tourist who cancels a trip prior to departure. If a tourist canceled a trip with a package price of $1700 and a departure date of September 4, on what day was the trip canceled?

(1)    the cancellation fee was $595

(2)    if the trip had been canceled one day later, the cancellation fee would have been $255 more.

答案选C， 我认为选B就可以了，因为1700*65%-1700*50%=255，所以，一定是在第16天前，所以就可以得到准确的日期了，不需要和（1）结合。大家说呢？

楼上的JJ, 1700* (50% - 35%)  also equals to 225 isn't it?

Have fun! BTW, when r u going to take it?

为什么不让我带笔记本啊？

11.5<Mile<12.5

285<gallon<295

若a<x<b

C<y<d  則今天要取x/y的範圍：

{a/c和a/d中取較小者}<X/y<{b/d和b/c中取較大的}