1、 On XY plane. If a line goes through Point A (A, 5), Is the slope of the line<0?
a. Line goes through (0, -2)
b. Line goes through (5, A)
2、 DS：一个含有10个数字(1,3,5,7,9,11,13,15,17,19)的数列的标准方差问题。问方差是否不变？
a: 抽掉2个数后，mean不变；
b: 抽掉2个数后，sum为90
On XY plane. If a line goes through Point A (A, 5), Is the slope of the line<0?
a. Line goes through (0, -2)
b. Line goes through (5, A)
a. K=(y1-y2)/(x1-x2)=(-2-5)/(0-A)=7/A. => there is no difinite answer if you don't know the value of A
For the first, I think it's B. Please note in the question, it actually said A is not equal to 5. Some people think the answer it's D, but I don't know what the first one can tell you, since we don't know what's the value of A.
I have posted a few questions yesterday, however I don't see it, is it because of this oversea users thing?
