CAA: Christian Anime Alliance

Well, tomorrow I am going to take part in a math competition and I am pretty up to date on most stuff but not on statistics. So if anyone out there could post some basic statistics rules and formulas before that time, it would be realy helpful.

I am talking about real simple ones like: If susan has a 11 cards, and 2 of them are black and the others are red, what is the probability that she will draw 5 cadrs in a row wihtout getting a black one.

and other problems allong that line. If anyone could help me with this before tomorrow that would be greatly apreciated. Thanks.

Well, you shouldn't leave things to the last minute- give yourself time to study. A full lesson on basic probability and statistics usually takes up the first chapter or two in most textbooks (which I will not duplicate). Peruse those first, and then come back with more specific questions about what you have trouble with. Any introductory book on probability and random processes would do, but Papoulis' or Garcia's books are probably the easiest to find. Stark and Woods' book though is unquestionably the best, although you may have trouble finding it.

For your particular example, the solution is simple. If you assume there is no replacement, then the total probability is simply the product of the proabilities of drawing a red card for each independant trial.

That is:
(9/11)*(8/10)*(7/9)*(6/8)*(5/7)

Each time you draw red card, the total number of red cards is reduced as is the total number of cards. If drawing with replacement is assumed then obviously the solution is trivial.

So what should you know?
1)The axioms of probability (and their set theoretic def'ns)
2)Joint/conditional probabilities and independence
3)Baye's theorem
4)Combinatorics.

All of these subjects are well covered in any elementary text book on probability and statistics, so a trip to your library is in order.

Thank you, that example was very helpful.

I actually have studied it to a certain extent before, I just need a little brushing up on it. I was planning on asking somone at school today, but I have been sick this weekend and therefor didnt go to school today.