1、
雨雪天230天,非雨雪天为898天
那么打出租的概率为
P=230/1128 * 1/2 + 898/1128 *0.1
=0.2 *1/2 +0.8 *0.1
=0.18
2、
X可能取0,2,20,40
P(X=0)=0.8 *0.9=0.72
P(X=2)=0.2 /2=0.1
P(X=20)=0.8 *0.1=0.08
P(X=40)=0.2 /2=0.1
所以期望值
EX=0+2*0.1 +20*0.08 +40*0.1
=0.2+1.6+4
=5.8
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