picked the right answer, not truly understand the question

lily88888UID: 2828533

A certain airport security scanner designed to detect explosive in luggage will alert the scanner's operator whenver the piece of luggage passing under the scanner contains an explosive. The scanner will erroneously alert the operator for only one percent of the pieces of luggage that contain no explosives. Thus in ninety-nine out of a hundred alerts explosives will actually be present.

The reasoning in the argument is flawed because the argument

E. Substitutes one group for a different group in the statement of a percentage.

I did not see the argument is flawed at all.

duijinxiaoziUID: 2585955

will erroneously alert the operator for only one percent of the pieces of luggage that contain no explosives.
-----------------------------------------------------------
有两种行李，一种有炸弹，一种没有炸弹（no  explosives）。
文章没有提到，有炸弹的行李，出错的概率。
-------------------------------------
也许，有炸弹的行李，一个都测不出来。
那么，概率就不是 99%。

umcwayneUID: 2674663

[LR][PT13-S2-Q24]