作者victim0130 (Maxwell)
看板GRE
標題[計量] 一題計量機經請教，謝謝!!
時間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。想請教B怎麼算出來??謝謝!!
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1F：→ cutepeebear : 因為中位數看的是最中間的數字，2000的80%=1600個ho 04/30 01:27
2F：→ cutepeebear : me<=$325000，也就是說有超過一半的數字<=$325000。 04/30 01:27
3F：→ cutepeebear : 假設最極端的案例有超過30%的home=$325000，中位數 04/30 01:27
4F：→ cutepeebear : 就是325000（因為比325000少的會低於50%）；如果小 04/30 01:27
5F：→ cutepeebear : 於30%的home=$325000，中位數一定小於325000，因此 04/30 01:27
6F：→ cutepeebear : 無論如何中位數一定會<=$325000 04/30 01:27
7F：→ victim0130 : 謝謝! :) 04/30 02:08