Page 1 of 1

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

Posted: 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?)

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

Posted: Tue Jun 29, 2010 3:53 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 :
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
Please can u tell what is wrong

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

$\mu'$ 1 = 0

$\mu'$ 2= 2/3

$\mu$2 = 2/3

var(X) = $\mu'$2 - $\mu$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
Please can u tell what is wrong

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

$\mu'$ 1 = 0

$\mu'$ 2= 2/3

$\mu$2 = 2/3

var(X) = $\mu'$2 - $\mu$2 = 2/3 - 2/3 = 0
$Var(X)=E(X^2)-[E(X)]^2=E(X^2)-0^2=E(X^2)=2/3$

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

Posted: Sun Jul 04, 2010 4:03 pm
Please can u tell what is wrong

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

$\mu'$ 1 = 0

$\mu'$ 2= 2/3

$\mu$2 = 2/3

var(X) = $\mu'$2 - $\mu$2 = 2/3 - 2/3 = 0
$Var(X)=E(X^2)-[E(X)]^2=E(X^2)-0^2=E(X^2)=2/3$

Thanks !!!