random var. X is -1, 0, 1 w/ equal probability (check ans)  TOPIC_SOLVED

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random var. X is -1, 0, 1 w/ equal probability (check ans)

Postby zorro on Tue Jun 29, 2010 2:27 am

Question :
X is a random variable which takes 3 values -1,0,1 with equal probability i.e. P(x=-1) = P(X=0) = P(X=1) = 1\3
Find E(X) and Var(X)
Solution :
E(X) = 0 (is this correct?)

var(X) = 0 (is this correct?)
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Re: random var. X is -1, 0, 1 w/ equal probability (check an

Postby Martingale on Tue Jun 29, 2010 3:53 am

zorro wrote:Question :
X is a random variable which takes 3 values -1,0,1 with equal probability i.e. P(x=-1) = P(X=0) = P(X=1) = 1\3
Find E(X) and Var(X)
Solution :


ok...

zorro wrote:E(X) = 0 (is this correct?)


Yes

zorro wrote:var(X) = 0 (is this correct?)


No
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Re: random var. X is -1, 0, 1 w/ equal probability (check an

Postby zorro on Wed Jun 30, 2010 2:27 am

Please can u tell what is wrong


My work ........
E(X) = 0

1 = 0

2= 2/3

2 = 2/3

var(X) = 2 - 2 = 2/3 - 2/3 = 0
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Re: random var. X is -1, 0, 1 w/ equal probability (check an  TOPIC_SOLVED

Postby Martingale on Wed Jun 30, 2010 4:48 am

zorro wrote:Please can u tell what is wrong


My work ........
E(X) = 0

1 = 0

2= 2/3

2 = 2/3

var(X) = 2 - 2 = 2/3 - 2/3 = 0


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Martingale
 
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Location: USA

Re: random var. X is -1, 0, 1 w/ equal probability (check an

Postby zorro on Sun Jul 04, 2010 4:03 pm

Martingale wrote:
zorro wrote:Please can u tell what is wrong


My work ........
E(X) = 0

1 = 0

2= 2/3

2 = 2/3

var(X) = 2 - 2 = 2/3 - 2/3 = 0





Thanks !!! :clap:
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