几道数学题, 求高人指点啊

fuchuan · 发表于 2012-8-11 21:59:31

1 Before being simplified, the instructions for computing income tax in Country R were to add 2 percent of one's annual income to the average(arithmetic mean) of 100 units of Country R's currency and 1 percent of one's annual income. Which of the following represent the simplified formula for computing the income tax, in Country R's cuurency, for a person in that country whose annual income is I?
A 50+ I/200
B 50+ 3I/100
C 50+ I/40
D 100+I/50
E 100+3I/100

2
Six countries in a certain region sent a total of 75 representative to an international congress, and no two countries sent the same number of representatives. Of the six countries, if Country A sent a second greatest number of representatives, did Country A send at least 10 representatives?
1) One of the six countries sent 41 representatives to the congress.
2) Country A sent fewer than 12 representatives to the congress.
A Statement 1 ALONE is sufficient, but statement 2 alone is not sufficient.
B Statement 2 ALONE is sufficient, but statement 1 alone is not sufficien.
C Both together are sufficient,
D Each state alone is sufficient.
E Together are not sufficient

3
A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner?(Two groups are considered different if at least one group member si different.)
A 48
B 100
C 120
D 288
E 600

4 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 Frech.

A Statement 1 ALONE is sufficient, but statement 2 alone is not sufficient.
B Statement 2 ALONE is sufficient, but statement 1 alone is not sufficien.
C Both together are sufficient,
D Each state alone is sufficient.
E Together are not sufficient

shinesalvation · 发表于 2012-8-11 22:13:21

第一题 2% I+(100+1% I)/2=50+I/40

fuchuan · 发表于 2012-8-11 22:17:08

谢谢啊，从你的推理才把题目看懂了，汗~~~~~~~~

mtryshy · 发表于 2012-8-11 22:20:08

第二道选E，就是都不充分，不能确保A的人数大于10。
第一个条件，一个国家41，A可以是11，然后其他4个国家瓜分23，A当然也可以是9
第二个条件A小于12，如果最大国家地人数非常多，A可以是10以内的任何大于5的数字
两个结合，当A是9时，4个国家瓜分25也很容易

shinesalvation · 发表于 2012-8-11 22:21:45

第三题 C3/10-C3/6=100?第四题 A？~

fuchuan · 发表于 2012-8-11 22:33:58

我第想法跟你一样，看来是prep的答案有点错误。

fuchuan · 发表于 2012-8-11 22:35:17

好同学，可以解释一下第三题吗？

第4题，我也选A了，prep的答案不是A：（

rebornkeke · 发表于 2012-8-11 22:44:38

第四题选B
可以设a，b，c 其中，a是只学习French的，c是只学习Japanese的，b是两者都学的；
题目已知是b+c>100, 且 b/(a+b)=4%, 问 a+b与b+c的数量关系；
1给出的条件是b=16，可以得到a值，a是大于100的，因此不能得到a和c的关系；
2 给出的是b/(b+c)=10%; 可以整理得到b和c的比例，其实也就能得到关系了；
因此单独2的条件即可；

fuchuan · 发表于 2012-8-11 22:51:23

第四题选B
可以设a，b，c 其中，a是只学习French的，c是只学习Japanese的，b是两者都学的；
题目已知是b+c>100, 且 b/(a+b)=4%, 问 a+b与b+c的数量关系；
1给出的条件是b=16，可以得到a值，a是大于100的，因此不能得到a和c的关系；
2 给出的是b/(b+c)=10%; 可以整理得到b和c的比例，其实也就能得到关系了；
因此单独2的条件即可；

-- by 会员 rebornkeke (2012/8/11 22:44:38)

谢谢，你的思路很清晰。
但是从条件2 这也不能确定 a+b 和 b+c 的数量关系啊？

而且这个学校里面是不是还有两种语言都不学的啊？

shinesalvation · 发表于 2012-8-11 22:52:05

第三题就是把所有可能的组合数减去一个SENIOR都没有的组合数就是至少有一个Senior的组合数。

第四题没注意at least。的确错了。。。

几道数学题, 求高人指点啊

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