1)
记k=i时的概率为p(i);
∑p(i)=p(1)+p(2)+...+到无穷
=b∑[1/k(k+1)]
=b∑[1/k - 1/(k+1)]
=b* lim [1/1 - 1/2 + 1/2 -1/3 +...+1/(n-1) - 1/n] (当n-->∞)
=b lim(1 - 1/n) (当n-->∞)
=b
而随机变量所有和应该为1,所以b=1.
2)
k=1,2,3,4,5,6;
P=C(6,k)(1/2)^k(1-1/2)^(6-k)
=C(6,k)(1/2)^6
而C(6,k)的值在k=3时取到最大,C(6,3)=20;
此时P=20/(2^6)=5/16
结论【K=3】