Math4-http://postimg.org/image/ls8pzrmrx/?
2016-04-05 5:23 pm
回答 (1)
2016-04-08 3:02 am
a)
P(1)+P(3)+P(5)+P(7)+P(9)=1
0.25+0.15+0.2+a+0.15=1
a=0.25
b)
E(Y)
=1*0.25+3*0.15+5*0.2+7*0.25+9*0.15
=4.8
c)
E(Y^2)
=(1^2)*0.25+(3^2)*0.15+(5^2)*0.2+(7^2)*0.25+(9^2)*0.15
=31
Var(Y)
=E(Y^2)-E(Y)^2
=31-4.8^2
=7.96
P(1)+P(3)+P(5)+P(7)+P(9)=1
0.25+0.15+0.2+a+0.15=1
a=0.25
b)
E(Y)
=1*0.25+3*0.15+5*0.2+7*0.25+9*0.15
=4.8
c)
E(Y^2)
=(1^2)*0.25+(3^2)*0.15+(5^2)*0.2+(7^2)*0.25+(9^2)*0.15
=31
Var(Y)
=E(Y^2)-E(Y)^2
=31-4.8^2
=7.96
收錄日期: 2021-04-18 14:47:34
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160405092318AAfjRG6