Question

急求几个关于算概率和期待值的问题.

Answer 1

1.E(X) = 100*20%*0.3 + (-100*10%*0.4) + 0.3*100*0

= 100*(0.06-0.04)

= 2（期待值为涨2万元）

2.P= (1/2)^4 = 1/16

3.P = (3 2) * (1/2)^2 = 3 * 1/4 = 3/4

4.设产品总数为N,P= (80%*N 4)/(N 4)

(A B) :就是 A 选B ,A 写在 B 上面.