、设连续型随机变量X的分布函数为
提问:、设连续型随机变量X的分布函数为
网友回答:
1、X 连续,所以,
F(2) = 1 = C * 2 - 2^2/2 - 1,C = 2;
F(1) = 2 * 1 - 1/2 - 1 = B * 1,B = 1/2;
F(0) = A = 0 * 1/2,A = 0;
2、f(x) = F'(x);
f(x) = (A)' = 0,x < 0;
= (1/2)(x^2)' = x,0 ≤ x < 1;
= [ 2x - x^2/2 - 1 ]' = 2 - x,1 ≤ x < 2;
= (1)' = 0,x ≥ 2;
3、P{ 1 ≤ x ≤ 4 } = F(4) - F(1) = 1 - 1/2 = 1/2 。