I recently won a 50/50 drawing in which my ticket was drawn from approximately 18,000 tickets. I also won the very next 50/50 drawing 2 weeks later in which my ticket was drawn from approximately 22,000 tickets. Using only these figures, what are the odds of winning those drawings back-to-back? (I realize most people purchased more than 1 ticket but there would be no way to know that.)

I believe it is 50/50.
Example, I am the 1,000,000th visitor on every site I go too. And there are millions on the Internet, But I constantly win.
Wonder what those odds are?

We need to be clear about the problem statement. There are two possible interpretations:

1. What is the probability of winning a olttery in week 1 where the odds are 1 in 18,000 followed by a lottery in week 2 where the odds are one in 22,000? Assuming that the week 1 and week 2 lottery drawings are independent events, then those odds are:
1/18000 x 1/22,000 = 1 in 396 million.

2. Given that you have won the week 1 lottery, what's the odds of winning week 2 as well? This is simply 1/22000, since the fact you won week 1 has no bearing on what may happen in week 2.

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Originally Posted by Stratmando

I believe it is 50/50.
Example, I am the 1,000,000th visitor on every site I go too. and their are millions on the Internet, But I constantly win.
Wonder what those odds are?

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On the Internet everyone is a winner! ;)