PREP PS1 188 求解！ 以前没讨论过

188.
                20383-!-item-!-187;#058&012808

Last month 15 homes were sold in Town X.  The average (arithmetic mean) sale price of the homes was $150,000 and the median sale price was $130,000.  Which of the following statements must be true?

大于165000的至少一个

[II]

[III]

(A) I only

(B) II only

(C) III only

(D) I and II

(E) I and III

答案A，

今天刚做模拟题，错了。请问这个165000怎么算出来的。 原来的PS1文档里面没有I选项，我这个是真好做到的。

谢谢！

我好像也错过

15×150000-8×130000=1210000

如果都小于165000，那么剩下的7个大于均值的数和为 165000×7=1155000<1210000

所以一必然是正确的

Which of the following statements must be true? 不用管它怎么算出来的，must be true就行了