1. Senior Member
Join Date
Dec 1969
Posts
171

Sorry, this isn&#039;t an ASP question, but it is for a game I am working on and thought someone could help. <BR><BR>I used an online calculator to determine the following and want to verify if it is correct but am not too good with odds:<BR><BR>I have a 1 in 10 chance of matching a number. If my number is a match, I have a 1 in 130 chance of picking a winning number. What are my odds of picking the winning number? <BR><BR>Using this calculator, http://www.csgnetwork.com/oddscalc.html, it says the combined odds are 1 in 9730. Can anyone help verify this?

2. Senior Member
Join Date
Dec 1969
Posts
171

oh, one more thing. What if I am presented with the 1 in 10 chance 7 times and each time that I made a match, I would increase my odds of picking a winning number - i.e. instead of 1 in 130, it would be 1 in 129 and then 1 in 128? <BR><BR>I could really use a formula for this :)

3. Senior Member
Join Date
Dec 1969
Posts
415

I think you need to describe this a little better. The way you originally described it (1 in 10 then 1 in 130), you&#039;re odds would be 1 in 1300. The odds of either event are not affected by the other so you simply multiply the odds of each action The odd of flipping a coin and getting heads (1/2) and then rolling a die and getting 6 (1/6) would be 1/2 * 1/6 = 1/12.<BR><BR>The case you&#039;re describing here is more complicated because the odds of the second event depend on the outcome of the first. You could figure out an answer, but ugh.. it&#039;s a lot tougher.

4. Senior Member
Join Date
Dec 1969
Posts
171

yes, its ugly

yes, the odds of the second event do depend on the outcome of the first. <BR><BR>thanks for your input, i guess i will need to sit down and crack open a stats book or something :)

5. Senior Member
Join Date
Dec 1969
Posts
415

Bernouli Trials

I think you have to consider all the possible outcomes of the 7 chances. 0 mathces, 1 match... 7 matches. Then multiply the odds of the first event by the odds of the second.<BR><BR>(odds of 0 matches) * 1/130 (odds of 1 match * 1/129) ...<BR><BR>There&#039;s a binomial distribution equation that will give you the odds of getting exactly X mathces in 7 tries (Your first event!) (http://mathworld.wolfram.com/BinomialDistribution.html)<BR><BR>Not sure what you do with all these results though. Add them up maybe? Bill might want in on this.

6. Senior Member
Join Date
Dec 1969
Posts
171

RE: Bernouli Trials

Ugh!!!

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