求助一道PREP的数学DS题，谢谢！！！

brucechung2011

23. 1653-!-item-!-187;#058&000843 At least 100 students at a certain high school study Japanese. If 4 percent of the students at the school who study French also study Japanese, do more students at the school study French than Japanese?

(1) 16 students at the school study both French and Japanese.

(2) 10 percent of the students at the school who study Japanese also study French.
答案：B


students at the school who study French also study Japanese和students at the school who study Japanese also study French这两句话表达的意思一样吗？



students at the school who study French also study Japanese和students at the school who study Japanese also study French这两句话表达的意思一样吗？

echo19872010

理解了。好聪明啊。谢谢谢谢

weixuan

不一定吧，题干说学J的人至少是100人，并没规定上限，由条件1只能推出F=400人。

echo19872010

那为什么我觉得1也是满足的呢? 即学法语又学日语的人是16个。。设学法语的人数是F   F4%=16 也能算出来学法语的总人数。。答案是不是应该选D 啊？？

brucechung2011

原来是这样，明白了 谢谢！

weixuan

不一样吧。设学日语的人数是J，学法语的人数是F，由条件2可得，则J和F交集部分（日语法语都学）的人数可表达成4%F或10%J，∴4%F=10%J, 化简后F=5/2J

brucechung2011

谢谢！

xiexiang

当然不一样，　数量相同，　但分数不同，　看除以哪个部分