1 the function f is defined for all positive integers n by the following rule. f(n) is the number of positive integers each of which is less than n and has no positive factor in common with n other than 1. If p is any prime number then f(p)=

A p-1 B p-2 C (p+1)/2 D (p-1)/2 E 2 answer:A

这题没怎么看明白，所以算了半天也没算清楚

2 一个数列｛－10，－6，－5，－4，－2.5，－1，0，2.5，4，6，7，10｝，任取一个数，使得(x-5)(x+10)(2x-5)=0成立的概率是多少？

A 1/12 B 1/6 C 1/4 D 1/3 E 1/2 answer: B

不太明白，要让这个等式成立应该是有3个数都符合条件，5，－10， 2.5，这样说来，概率难道不是3/12=1/4吗？

3 R bought two kind of candy bars, C and T, that came in packages of 2 bars each. He handed out 2/3 of C bars and 3/5 of the T bars. Howmany packages of C bars did R buy?

1) R bought 1 fewer package of C bars than T bars

2) R handed out the same number of each kind of candy bars

answer: C

不明白packages和 number of bars是什么关系？

完了完了，我脑子是不是进水了？？？这么多题都不会！！

恳请大家帮忙！！！谢谢大家了！！

1.f(n)定义为这样一个数目：所有小于n的且与n没有公因子（除1之外）的正整数的数目。

又说p是一个质数，那当然前面从1到P-1这些数都是满足条件的，所以有p-1个。

2.赞同你的意见

3.设C bars有Xpackages,T bars有Ypackeges.

(1)Y-X=1

(2)2/3X=3/5Y

谢谢解答！

第二题我看清楚了，数列中没有 5 ！！！，所以是B是答案

这题出的真黑呀！！！大家要小心哦！！