急啊！！问几条ds的题目，在线等，老错老错的

dpzixuan89

each employee on a certain task force is either a manager or a director. what percent of the employees on the task force are directors?
1 the average  salary of managers on the task force is 5000d less than the average salary of all employees on the task force.
2 the average salary of directors on the task force is 15000d greater than the average salary of all employees on the task force.
选C


6 countries in a certain region went a total of 75 representatives to a international congress, and no 2 countries sent the same number of representatives of the 6 countries. if country A sent the second greatest number of representatives,did country A send at least 10 representatives.
1,one of the 6 countries sent 41 representatives to the congress.
2, country A sent fewer than 12 representatives to congress
选E


还有一题这种的
15 homes were sold in town X, the average sale price of homes was 150000 and median sale price is 130000.下面那个一定对
1）at least one of the homes was sold for more than 165000
2) at least one of the homes was sold for more than130000 and less than 15000
3) at least one of the homes was sold for less than130000
答案是1是肯定对的

dpzixuan89

怎么没人理我啊？？？
我就是想问一下这几条题的解题方法。。。我是想不通。我DS超级不行

傲骨

第一题:
设manager x人 每人工资a  director y人 每人工资b
条件1可知:a=[(ax+by)/(x+y)]-5000
条件2可知:b=[(ax+by)/(x+y)]+15000
最后问的是y/(x+y)=?
你把条件1和2联立起来能求出x和y关系 是x/y=3/1吧 那就选C了

傲骨

第二题:
就算条件1和条件2联合起来
有以下情况-- 议员人数从大到小(A是第2个)
41 11 8 7 6 2 和 41 9 8 7 6 4
所以A不确定是否大于等于10

dpzixuan89

那第三题呢？？？

傲骨

第三题
如果前14个都是130000 最后一个是430000 满足中数是130000 平均数是 150000
但是条件2和3都不对

dpzixuan89

谢谢!

doreen蝶

第三题，
从大到小将15个数排列，前7个平均数设为X，后七个平均数Y，则这15个数可以看成
X,13000,Y
X+13000+Y=15000*15
(X+Y)/2=16500
Y<X, 所以前七个数平均数X>16500

cqrain

请问第一题, 你是怎么推出X/Y= 3的?
设manager x人 每人工资a  director y人 每人工资b
条件1可知:a=[(ax+by)/(x+y)]-5000
条件2可知:b=[(ax+by)/(x+y)]+15000
最后问的是y/(x+y)=?
你把条件1和2联立起来能求出x和y关系 是x/y=3/1吧 那就选C了

傲骨

通分阿 条件1可以化简为5000=[y(b-a)]/(x+y)
条件2:15000=[x(b-a)]/(x+y)