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?)}

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?)}

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

var(X) = 0

- Martingale
**Posts:**335**Joined:**Mon Mar 30, 2009 1:30 pm**Location:**USA-
**Contact:**

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

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

My work ........

E(X) = 0

var(X) =

- Martingale
**Posts:**335**Joined:**Mon Mar 30, 2009 1:30 pm**Location:**USA-
**Contact:**

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

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 !!!