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

Posted: **Tue Jun 29, 2010 2:27 am**

by **zorro**

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?)}

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

Posted: **Tue Jun 29, 2010 3:53 am**

by **Martingale**

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...

E(X) = 0 _{(is this correct?)}

Yes

var(X) = 0 _{(is this correct?)}

No

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

Posted: **Wed Jun 30, 2010 2:27 am**

by **zorro**

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

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

Posted: **Wed Jun 30, 2010 4:48 am**

by **Martingale**

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

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

Posted: **Sun Jul 04, 2010 4:03 pm**

by **zorro**

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 !!!