题目(4)常数b=()时,P_(k)=(b)/(k(k+1))(k=1,2,...)为离散型随机变量的概率分布.A. 2B. 1C. (1)/(2)D. 3(4)常数b=()时,$P_{k}=\frac{b}{k(k+1)}(k=1,2,\cdots)$为离散型随机变量的概率分布.A. 2B. 1C. $\frac{1}{2}$D. 3题目解答答案B. 1