求大神解答两道数学题~要考啦。。。急求！

xiaoming2013

1. Are at least 10 percent of the people in the Country X who are 65 years old oroler employed?
   (1)In the Country X, 11.3 percent of the population is 65 years old or older.
   (2)In the Country X, of the population 65 years old or older,20 percent of the men and 10 percent of the women are employed.
  正确答案B
  我明白为什么（1） insufficient ,但不知道为什么（2）sufficient


2.Alice's take-home pay last year was the same each month,and she saved the same fraction of her take-home pay each month.The  total amount of money that she had save at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save. If all the money that she saved last year was from her take-home pay, what fraction  of her take-home pay did she save each month?
正确答案1/5

xiaoming2013

啊啊啊  刚短路了。。。第一题懂了。。。囧 求第二题~~~~

Stellar0223

prep上的吧~同求第二题，算了半天没算明白！！

fairymandy

假设每个月赚的钱是1，取出其中的x存起来，一年就是存了12x，然后这个12x是她每月赚的但是没有存起来的3倍，所以12x=3（1-x）得出x=1/5，然后除以总数1，每个月她存的钱占赚的钱的1/5

jingjingruye

xiaoming2013 发表于 2013-8-18 13:27
啊啊啊  刚短路了。。。第一题懂了。。。囧 求第二题~~~~

没明白第一题。。。求解释

jingjingruye

设take home pay I ，fraction X    题意： 12xI=3（1-x）I  得答案1/5

q求解释第一题。。。。没看懂

hwj86160110

题目是问65或以上被雇佣的比例，第一题条件一没有employed所以判断无用，条件二，就算65岁或以上全是女的也有10%所以大于等于10%可以判断
第二题 x+y=1
            12x=3y

renazha

一年的saving 是一个月没存下的3倍，应该你是没看清题目  X%*P*12=3*（100-X)%*P, X%=20%

xiaoming2013

这样哦~~~thx 都是因为没看懂题。。。第二题没看到是年的和月的比  
第一题以为是这个国家里至少有10%的人既大于等于65 又employed。。。其实是65里面有多少employed。。。都是语言惹的祸。。。