Thread: Marginal Distribution of Rolling 2 Dice

I know this is a simple problem but I can't think the correct way to write it out.

Let X= no. on die 1 and Y= no. on die 2

f(x,y) = {1/13 for x and y = 1,2,3,4,5,6
0 otherwise}

1.Find the marginals of X and Y?

2. Are X and Y independent?
I know they are indepented because f(x,y)=g(x)h(y)
That is true, right?

I just can't come up with the correct way to solve for the marginals. Will each marginal end up just being 1/6?

Originally Posted by meks08999

I know this is a simple problem but I can't think the correct way to write it out.

Let X= no. on die 1 and Y= no. on die 2

f(x,y) = {1/13 for x and y = 1,2,3,4,5,6
0 otherwise}

1.Find the marginals of X and Y?

(is that even a probability distribution?)



The marginal distribution of ( a discrete RV) is defined by:

2. Are X and Y independent?
I know they are indepented because f(x,y)=g(x)h(y)
That is true, right?

I just can't come up with the correct way to solve for the marginals. Will each marginal end up just being 1/6?

How can you know this without knowing the marginals?



where is the joint probability of and , the marginal for and the marginal for is a necessary and sufficient condition for independence, but you need to show that it is true (or false).


CB

With how you asked if it was a probability distribution, it what I don't understand. I don't see it as a probability distribution either but we were told to find the marginals of this. So, I'm just confused.

I know that I need to prove it true, but I have a strong feeling that it will be true.