以下是引用hitlzc在2006/6/19 15:48:00的发言:选E。 赞同下面看法。 看“赞同”的意思,答案要选D,可是feifei数学下载打印后的答案却是E啊?谁能再给讲讲这道题,看不懂啊。谢谢 找到了原题(注意一个数字的不同,feifei CD网站下载的 2/5,在下面的题中变成了3/5)不过我想道理是一样的,请明白的人给解释解释如何?谢谢! Of the students who eat in a certain cafeteria, each student either likes or dislikes lima beans and each student either likes or dislikes Brussels sprouts. Of these students, 2/3 dislike lima beans; and of those who dislike lima beans, 3/5 also dislike Brussels sprouts. How many of the students like Brussels sprout but dislike lima beans?
1). 120 students eat in the cafeteria.
2). 40 of the students like lima beans. 该网站Ron的解释如下(答案也是D,跟CD上feifei下载的答案E也有出入) (1) 120 students total --> 40 YES LIMA, 80 NO LIMA split up the NO LIMA crowd: --> 3/5 of 80 = 48 NO LIMA + YES BRUSSELS --> 2/5 of 80 = 36 NO LIMA + YES BRUSSELS sufficient
(2) the fraction 2/3 tells you that the other 1/3 like lima beans (so that the ratio YES LIMA : NO LIMA is 1 : 2) therefore, x (the unknown multiplier) = 40, and 2x is therefore 80 --> 40 YES LIMA, 80 NO LIMA rest of the problem proceeds as above sufficient
answer = d 答案到底是什么?如何解?
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