• Sep 25th 2006, 11:10 PM
10219929
Hi, I would appreciate any guidance to do this exercise. I'm a lawyer and I'm quite lost with the subject:

Te question is:

Consider the following probability distribution:

X P(X)

-1 0.17
2 0.15
5 0.40
8 0.18
11 0.10
1.00

E(X)= _ _. _ _ _ _
V(X)= _ _. _ _ _ _

Mauricio
• Sep 26th 2006, 07:21 AM
JohnM
Quote:

Originally Posted by 10219929
Hi, I would appreciate any guidance to do this exercise. I'm a lawyer and I'm quite lost with the subject:

Te question is:

Consider the following probability distribution:

X P(X)

-1 0.17
2 0.15
5 0.40
8 0.18
11 0.10
1.00

E(X)= _ _. _ _ _ _
V(X)= _ _. _ _ _ _

Mauricio

E(X) = expected value = summation of X*P(X) --> same as a weighted average

V(X) = variance = summation of [ X - E(X) ]^2 * P(X)
• Sep 26th 2006, 03:14 PM
10219929
Thanks John
For V(X), that means that I have to use the sumation of all X values, plus the result of the sumation of E(X)? Sorry mate, can you give just one example using the numbers? Thanks a lot. Mauricio
• Sep 26th 2006, 03:30 PM
JohnM
Quote:

Originally Posted by 10219929
For V(X), that means that I have to use the sumation of all X values, plus the result of the sumation of E(X)? Sorry mate, can you give just one example using the numbers? Thanks a lot. Mauricio

Yes, for V(X) you will use the result from computing E(X).

Here's an example:
Expectation