Probability Distributions: scratch-and-win promotion

Kiran

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Joined
Jan 6, 2008
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4
1. Suppose that one third of the cards in a scratch-and-win promotion gives a prize.
a) what is the probability that you will not win a prize until your second try?
b) what is the probability of winning within your first two tries?
c) what is the expected number of cards you would have to try before winning a prize?

pehaps i must be more specific

i realize that this invloves geometric distribtution b/c there is a "waiting time". i also realize that p=0.33 or 1/3 and q=0.67 or 2/3. i think you can use the formula

P(x)= q^x p but i do not know what x would be. i have no ther thoughts, plz help
 
What are your thoughts? What have you tried? How far have you gotten? Where are you stuck?

Please be complete. Thank you! :D

Eliz.
 
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