问几个prep的数学题

tantan0532

39.   3582-!-item-!-187;#058&003470

For the students in class A, the range of their heights is r centimeters and the greatest height is g centimeters.  For the students in class B, the range of their heights is s centimeters and the greatest height is h centimeters.  Is the least height of the students in class A greater than the least height of the students in class B ?

 

(1) r < s

 

(2) g > h

答案是c

64.   5320-!-item-!-187;#058&004563

Are at least 10 percent of the people in Country X who are 65 years old or older employed?

 

(1) In Country X, 11.3 percent of the population is 65 years old or older.

 

(2) In Country X, of the population 65 years old or older, 20 percent of the men and 10 percent of the women are employed.

答案是b

70.   6067-!-item-!-187;#058&004849

Is the integer x divisible by 6 ?

 

(1) x + 3 is divisible by 3.

 

(2) x + 3 is an odd number.

 答案是c

tantan0532

为啥没人帮忙给看看啊

lyricsea

39题肯定是C呀

A班最矮的就是g-r，B班最矮的就是h-s

A班高于B班，就是g-r〉h-s，即g+s〉h+r

两个条件满足时，上述不等式成立

64题，题目即是求大于等于65岁的人中是不是至少有百分之10的受雇。

第一个条件肯定无法满足

再看第二个。设全国大于等于65岁的人有s个，其中男的a个，女的b个。则如果0.2a+0.1b〉0.1s题目就成立。其中a+b=s，换算的结果是上述不等式成立，所以条件二满足。

70题，题目问x是否被6整除

条件一，3+x是3的倍数，则3+x=3k（k+1，2，3……），3+x就可能为3，6，9，12。。。。不满足

条件二，3+x是偶数，根据条件一，则刚好是3k的偶数倍，所以满足。

所以选C