数学试题讲解

设离散型随机变量

X

的分布函数

F (x) = {\begin{array}{cc} 0 & x < 0 \\ a & 0 \leq x < 2 \\ \frac{3}{4} - a & 2 \leq x < 3 \\ a + b & x \geq 3 \end{array}

, 且

P (X = 3) = \frac{1}{2}

则

a, b

的值分别为

\frac{1}{3}, \frac{1}{6}

\frac{1}{6}, \frac{1}{3}

\frac{1}{3}, \frac{2}{3}

\frac{1}{4}, \frac{3}{4}