作者victim0130 (Maxwell)
看板GRE
标题[计量] 一题计量机经请教，谢谢!!
时间Sun Apr 30 01:16:10 2017
In a neighborhood consisting of 2,000 homes, 80 percent of the homes
are valued at $325,000 or less. Which of the following statements
about the values of the homes in the neighborhood must be true?
Indicate all such statements.
A. The average (arithmetic mean) value is at most $325,000.
B. The median value is at most $325,000.
C. At most 400 homes have values greater than $325,000.
答案: BC。想请教B怎麽算出来??谢谢!!
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1F：→ cutepeebear : 因为中位数看的是最中间的数字，2000的80%=1600个ho 04/30 01:27
2F：→ cutepeebear : me<=$325000，也就是说有超过一半的数字<=$325000。 04/30 01:27
3F：→ cutepeebear : 假设最极端的案例有超过30%的home=$325000，中位数 04/30 01:27
4F：→ cutepeebear : 就是325000（因为比325000少的会低於50%）；如果小 04/30 01:27
5F：→ cutepeebear : 於30%的home=$325000，中位数一定小於325000，因此 04/30 01:27
6F：→ cutepeebear : 无论如何中位数一定会<=$325000 04/30 01:27
7F：→ victim0130 : 谢谢! :) 04/30 02:08