We want P(X ≥.6). Because X is continuous, this is the same as P(X > .6) = 1 – P(X ≤ .6) = F(.6) = 3(.6)2 – 2(.6)3 = .648. One way to interpret this is that almost 65% of all counties have an elderly employment rate of .6 or higher.

红色部分是否应该为： 1 – P(X ≤ .6) = 1-F(.6)

如各位所知，F(*) 是积累分布函数。

谢谢。BTW,发现这样令人迷惑的地方 那个 教师手册 的答案中还有好多...