Question

离散型随机变量的均值

Answer 1

由题意知ξ的可能取值是0,1,2,3,

P（ξ=0）=0.4×0.4×0.4=0.064

P（ξ=1）=0.4×0.4×0.6=0.096

P（ξ=2）=0.4×0.6=0.24

P（ξ=3）=0.6,

∴Eξ=1×0.096+2×0.24+3×0.6=2.376

故答案为：2.376