[求助]PP的几道数学题，NN们帮忙看下吧~（新加了几道）

1. Are X and Y both positve?
1. 2X-2Y=1
2. X/Y>1

答案是C，可是我怎么算算是E

1. 2的N次方=N的2次方，问N有几个？ 答案两个，请问是那两个呢？

1. If n and m 是整数，3的4n+2次方 is divided by 10, what is the remaider?
1. n=2
2. m=2

答案竟然选B，我真怀疑是题目出错了，可这是PREP~~

1. A law firm has 4 senior partners and 6 junior partners, How many different groups of 3 partners have at least one of them is senior partner?(Two groups are considered different if at least one group member is different)

答案是100，

1. 2/3 of 60 animals a firm has is either cow or pig, 求 how many cows?
1. the firm has more than twice as many cows as pigs
2. the firm has more than 12 pigs.

答案选C

拜托给出解题的思路，谢谢啦，快考试了，紧张中。。。。

Are X and Y both positve?

1. 2X-2Y=1
2. X/Y>1

1=>x>y，且x=y+1/2 (i)

2=>x、y同号(ii)

将x=y+1/2代入2记得1+1/(2y)>1==>y>0,加上(ii),所以x>0,y>0

选C

1. if each term in the sum a1+a2+……an, is either 7 or 77 and the sum equals 350,which of the following could be equal to n?

           A 40                B42  

每项都是7的倍数，350＝7×50. 7＝7×1，77＝7×11.设有m个7，n个77，m+11n=50，则最终答案文m+n可能是多少?

当m＝39时，n＝1，此时m+n=40. (A)单独成立。

实际上可以由n来进行可能的组合，因为n是11的个数。

n=0,m=50==>m+n=50;

n=1,m=39==>m+n=40;

n=2,m=28==>m+n=30;

...

所以选A

3

不知道还有什么选项，可以这样：从350里面去掉77的倍数，

只有1-77， 2-154，3-231，4-308几种可能

然后从350分别里面减掉以上数字，得到的结果用7来除。

比如，350-77=273=7x39

然后39+1=40就搞定了

1. Before being simplified, the instructions for computing income tax in Country R were to added 2 percent of one's annual income to the average of 100 units of R's currency and 1 percent of one's annual income, what is the simplified formula for computing the income tax if one's annual income is X?

            A 50+ X/200     B 50+3X/100     C  50+X/40     答案选 C       题目压根没看懂。。。。。。

 2% x + (100 + 1%x)/2
    

1=>x>y，2=>x、y 为什么丫？怎么的出来的

1. 2的N次方=N的2次方，问N有几个？ 答案两个，请问是那两个呢？

         是2^2=2^2和2^4=4^2吧？

1. A law firm has 4 senior partners and 6 junior partners, How many different groups of 3 partners have at least one of them is senior partner?(Two groups are considered different if at least one group member is different)

答案是100，

我的做法是C(10,3)-C(6,3)=100, 不清楚这种做法对不对！

1. 2的N次方=N的2次方，问N有几个？ 答案两个，请问是那两个呢？n=0 or 2