有爱的NN。。。快出现吧。。。GWD数学~~~

piaoface

Town T has 20,000 residents, 60 percent of whom are female. What percent of the residents were born in Town T?

(1) The number of female residents who were born in Town T is twice the number of male residents who were not born in Town T.

(2) The number of female residents who were not boen in Town T is twice the number of female residents who were born in Town T

答案是B。
求NN分析下~~~~

zhadanking

第2个条件没有提到male怎么能确定所有居民的比例呢。答案错了。选C。

piaoface

第2个条件没有提到male怎么能确定所有居民的比例呢。答案错了。选C。

-- by 会员 zhadanking (2011/11/18 23:40:52)

我也深深觉得是C。。。谢谢了zhadanking。。。你总是第一时刻出现啊。。。NN

stevenliang

简单设：没生在T的，FNBT，MNBT，生在t的，FBT，MBT好吧~~
结合题干已知：条件一：fnbt+fbt=12000
                                      mbt+mnbt=8000
                                      fbt=2mnbt                三个方程四个未知数，不行吧
                         条件二：同理三个方程四个未知数，还是不行
     条件一+条件二刚好，四个方程四个未知数，可解~~

stevenliang

第2个条件没有提到male怎么能确定所有居民的比例呢。答案错了。选C。

-- by 会员 zhadanking (2011/11/18 23:40:52)

大NN，求解一道数学题，If n is the product of the integers from1 to 20 inclusive, what is the greatest integer k for which 2k is a factor of n? 我认为答案应该是n/2，但是答案貌似是什么16还是18什么的，这个怎么解？