What is the probability that a student randomly selected from a class of 60 students will be a male who has brown hair?

(1) One-half of the students have brown hair.

(2) One-third of the students are males.

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 sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

为啥两个条件在一起还不充分啊？ 怎么也想不通

如果就题论题，我可以给你解释，这道题目也很简单。可是没有用的。

因为你的思维方法需要改进，其实原因你也说了，就是缺乏分析。不能简单的认为，好像有两个条件，答案好像能推出来，就认为选C，这是不好的。你必须了解这两个条件告诉你了什么东西，然后才能判断。

如果你明白probability的定义，那么你再做做，应该能做出来。如果对probability不熟悉，你可以下载CXD或者钱勇强的math看看怎么定义的，基本的概率题目怎么推导的，这样好点。

30个brown, 20个males.

60个人，请问棕头男的概率是多少？

很明显：E