1. ## Find the Variance

So here is my question:

Here for the r.v. Degree, 1 represents a leading role and 2 represents a secondary role. What is the variance of the r.v. Degree?

Degree Females Males Sigmas
1 7 3 10
2 28 12 40
Sigmas 35 15 50

I do not understand how to get the variance from this. Any help on the procedure would be appreciated!

2. Originally Posted by Mistini
So here is my question:

Here for the r.v. Degree, 1 represents a leading role and 2 represents a secondary role. What is the variance of the r.v. Degree?

Degree Females Males Sigmas
1 7 3 10
2 28 12 40
Sigmas 35 15 50

I do not understand how to get the variance from this. Any help on the procedure would be appreciated!
...What?

3. The numbers kinda scooted closer together, but for the top row it should read 7 females, 3 males and a total of 10 for for the leading role. Then the second role is 28 females and 12 males with a total of 40 for that row. I just have to find the variance of both rows. Instead of 1 and 2, you can replace them with Leading Role and Secondary Role if that helps. I just dont understand which numbers to use to find the variance.

Maybe if I reword it?

Secondary 28females 12 males

What is the variance among the roles?

4. Originally Posted by Mistini
The numbers kinda scooted closer together, but for the top row it should read 7 females, 3 males and a total of 10 for for the leading role. Then the second role is 28 females and 12 males with a total of 40 for that row. I just have to find the variance of both rows. Instead of 1 and 2, you can replace them with Leading Role and Secondary Role if that helps. I just dont understand which numbers to use to find the variance.

Maybe if I reword it?

Secondary 28females 12 males

What is the variance among the roles?
Variation in gender for the leading role:

$\displaystyle E[X] = \frac{7+3}{2} = 5$

$\displaystyle E[X^2] = \frac{(7^2 + 3^2)}{2} = 29$

$\displaystyle Var(X)= E[X^2] - (E[X])^2 = 29 - (5)^2 = 4$

Now do the same for the second role.