You are Here: Home >< Maths

Marginal distribution of a discrete random variable-- statistics Watch

1. Can someone please help me figure out how this joint prob. distribution is drawn together? I know how the 0 values and the one that's given is obtained, pretty much clueless about the rest, I also know that there are 28 ways of choosing 2 refills from 8.
2. (Original post by rextra)
...
Consider the cell relating to X=0,Y=0.
If they're not blue and not red, then both choices must be green.
So, we want P(1st choice is green) X P(2nd choice is green) = 3/8 x 2/7 = ...

Or X=1,Y=0.
So, one blue refill, and no red. Well, again if it's not red and it's not blue, it must be green.

So, we want P(1st choice blue) X P(2nd choice is green) + P(1st choice is green) X P(2nd choice is blue) = 3/8 X 3/7 + 3/8 X 3/7 = ....

I think you should be able to fill in the remainder yourself now - have a go.
3. (Original post by ghostwalker)
Consider the cell relating to X=0,Y=0.
If they're not blue and not red, then both choices must be green.
So, we want P(1st choice is green) X P(2nd choice is green) = 3/8 x 2/7 = ...

Or X=1,Y=0.
So, one blue refill, and no red. Well, again if it's not red and it's not blue, it must be green.

So, we want P(1st choice blue) X P(2nd choice is green) + P(1st choice is green) X P(2nd choice is blue) = 3/8 X 3/7 + 3/8 X 3/7 = ....

I think you should be able to fill in the remainder yourself now - have a go.
wow, thanks! posted a new q just now, if you can help me figure this one out that'd be mint x http://www.thestudentroom.co.uk/show...2#post42085002

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 4, 2013
Today on TSR

What is the latest you've left an assignment

And actually passed?

Simply having a wonderful Christmas time...

Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Chat with other maths applicants

Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.