small math question <we hope>

[shutupndeal]

I may have asked this BUT if I did I cant find it anywhere and this is the only place this question really belongs and at least I know where to find it now so..........

I was trying to find out something the other day and I had one of those totally foggy days where I actually broke out a deck of cards and STILL wasnt sure I was correct, this was my problem. I want to know just how the formula would be written to show this probability example.

What are the odds of me catching 2 spades on the flop if I have the ace and queen of spades on my hand preflop?
I was getting 20-1 but it doesnt seen correct so Id like to see it written. Also if I wanted to figure the exact odds of only one spade falling or all 3 how would that be done? I did so well in statistics in school I cant believe my mind is this rotted! : ) Anyone ever check out that "Holdem" odds book, what kinda stuff is in that?

[BruceZ]

There are 11 flush cards and 39 non-flush cards, and there are C(50,3) possible flops ignoring order.

no spades: C(39,3) / C(50,3) = 0.46627551

1 spade: 11*C(39,2) / C(50,3) = 0.415867347

2 spades: C(11,2)*39 / C(50,3) = 0.109438776

3 spades: C(11,3) / C(50,3) = 0.008418367
-----------------------------------------------------------
total = 1


I'll post a review of Petriv's book once I've finished examining it. Here are some earlier comments (http://forumserver.twoplustwo.com/showthreaded.php?Cat=&amp;Board=probability&amp;Number=365 370&amp;Forum=All_Forums&amp;Words=Petriv&amp;Match=Entire%20P hrase&amp;Searchpage=0&amp;Limit=25&amp;Old=1year&amp;Main=365114&amp; Search=true#Post365370) I have made about it.

[pretender2k]

According to Ken Warren's book I quote:

"The chance of of flopping a four-flush when you are suited is 10.944%. the chance of flopping a four-flush when you are not suited is 2.245%."