# I'm a novice chem major not math

• Jul 23rd 2012, 03:50 PM
ASCP
I'm a novice chem major not math
I woululd like to know how to go about predicting odds and probability.

I introduced raffle card game to my rotary club. You have as standard 52 card deck and draw out one card a week until you draw an ace which wins. The pot is now \$3,500 and we have drawn out 37 cards with out drawing an ace. There is no replacement. It seems to me this would begin to be astronomical that we could draw out 37 cards in a row and not get an ace.

I would also like to know he formula for odds and probability.

Thanks
• Jul 23rd 2012, 04:35 PM
pickslides
Re: I'm a novice chem major not math
Here's a thought. The probability of drawing an ace in the first week is 4 in 52.

If an ace is not drawn in the first week then the probability of drawing an ace in the second week is 4 in 51, 4 aces remain, but only 51 cards.

Therefore the probability of not drawing an ace in the first two weeks is $\frac{52-4}{52}\times \frac{51-4}{51}$

Build on this idea, can you see a pattern as the weeks increase?