Thread: Basic Statistics. Help please

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

They ask (answer to four decimal places):

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


Your help is much appreciated.

Mauricio

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

They ask (answer to four decimal places):

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


Your help is much appreciated.

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)

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

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