OG49

alicejingli

A milepost on the towpath read “21” on the side facing the hiker as she approached it and “23” on its back. She reasoned that the next milepost forward on the path would indicate that she was halfway between one end of the path and the other. However, the milepost one mile further on read “20” facing her and “24” behind.

Which of the following, if true, would explain the discrepancy described above?

(A) The numbers on the next milepost had been reversed.
(B) The numbers on the mileposts indicate kilometers, not miles.
(C) The facing numbers indicate miles to the end of the path, not miles from the beginning.
(D) A milepost was missing between the two the hiker encountered.
(E) The mileposts had originally been put in place for the use of mountain bikers, not for hikers.

虽然选到了正确答案，但是还是对这替感到很奇怪。大家可以帮忙分析分析吗

感谢！

linmeimei

C is the answer.  This is another common sense question.

Originally the hiker assumes that the facing numbers indicate miles from the beginning and the back numbers indicates miles to the end of the path.  So he is 21 miles from the beginning and 23 miles from the end. Therefore he reasons that if he advances 1 more mile away from the beginning, the next mile post should have 22 miles on the facing number and 22 miles on the back number, indicating it is the middle point of the path.

But this is not the case.  By moving 1 mile away from the beginning, the facing number acturally decreases 1 to 20 miles, while the back number increases 1 to 24 mile. So the 1 mile increase is added to the back number which has to indicate miles from the beginning.  Therefore, the facing numbers indicate miles to the end of the path, not miles from the beginning.

seuhongkai

能否解释一下这道题的逻辑？