Math Is Fun Forum

titusland

Member

Registered: 2010-09-20

Posts: 9

Probability Problem

Hello; please help me with this question:

There are 50 tickets.
3 of them are winning tickets.
Now, I bought 4 out of the 50 tickets.
I want to know the probabilities of
a) My tickets containing all 3 winning tickets, and
b) I do not win anything.

Thanks in advance.

Last edited by titusland (2010-09-20 11:12:15)

Fruityloop

Member

Registered: 2009-05-18

Posts: 143

Re: Probability Problem

Try using the hypergeometric distribution.  You have two groups of tickets, winning and losing.
How many ways can you select 0 winning and 4 losing tickets?
How many ways can you select 3 winning and 1 losing ticket?
Use those numbers divided by the total number of ways of selecting 4 out of 50 tickets and you've got your answer!

soroban

Member

Registered: 2007-03-09

Posts: 452

Re: Probability Problem

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titusland

Member

Registered: 2010-09-20

Posts: 9

Re: Probability Problem

Thanks to both of you for answering this question!
I got it now!
Now, if I had a jar of virtual cookies I'd give you guys some;
but it is mathematically provable that I do not have such a thing.

Last edited by titusland (2010-09-21 09:21:52)

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: Probability Problem

Yes, it is a typical hypergeometric problem.
For more teachings on probability distributions,
I would recommend this book
Models for Probability and Statistical Inference: Theory and Applications
by James H. Stapleton

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X'(y-Xβ)=0

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: Probability Problem

It is a pity that there are few books explaining useful distributions.

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X'(y-Xβ)=0