Question

高三一道概率题

Answer 1

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