Binomial Distribution

[LetYouDown]

Friend asked me this last night...just want to verify, as I haven't really done it in a while so I'm a bit fuzzy. Assume you want the probability of rolling a fair die 5 times and getting a specific number exactly 3 times.

I just used a rather hazy non-cumulative Binomial Distribution as:

P = C(5,3) * 1/6^3 * (5/6)^2 = 3.215%

If I recall correctly, using the cumulative Binomial Distribution would give me the odds that a specific number is rolled <= 3 times?

These functions can both be done in Excel as:

=BINOMDIST(3,5,1/6,FALSE) and
=BINOMDIST(3,5,1/6,FALSE) respectively?

Sorry for the stupid question, I just want to verify/get my math brain back in gear.

[BruceZ]

[ QUOTE ]
Friend asked me this last night...just want to verify, as I haven't really done it in a while so I'm a bit fuzzy. Assume you want the probability of rolling a fair die 5 times and getting a specific number exactly 3 times.

I just used a rather hazy non-cumulative Binomial Distribution as:

P = C(5,3) * 1/6^3 * (5/6)^2 = 3.215%

If I recall correctly, using the cumulative Binomial Distribution would give me the odds that a specific number is rolled <= 3 times?

These functions can both be done in Excel as:

=BINOMDIST(3,5,1/6,FALSE) and
=BINOMDIST(3,5,1/6,<font color="red">TRUE</font>) respectively?

Sorry for the stupid question, I just want to verify/get my math brain back in gear.

[/ QUOTE ]

[LetYouDown]

Wow, someone pays attention =). Yeah, obviously I meant TRUE. Otherwise correct?

It's been a while since I've really messed with math, but I'm really interested in re-learning a lot of this stuff. Obviously this function is pretty trivial. Do you (or anyone) have a good course of action to get me back in the game? I just need a logical progression of things to refresh myself with...starting simple and moving up in complexity.

[BruceZ]

[ QUOTE ]
Wow, someone pays attention =). Yeah, obviously I meant TRUE. Otherwise correct?

[/ QUOTE ]

Yes.

If you don't want to spend $$, here is a free pdf of a book on probability from Dartmouth Introduction to Probability

Of course some of the sections are not applicable to Poker (such as binomial distributions).

[bobman0330]

It is both hilarious and awesome that you used the phrase "get back in the game" to refer to studying and applying math.

[BruceZ]

I like the book Probability and Statistics by Morris DeGroot.

[LetYouDown]

[ QUOTE ]
It is both hilarious and awesome that you used the phrase "get back in the game" to refer to studying and applying math.

[/ QUOTE ]
Not sure why that's so funny...but I'll take your word for it =).

Thanks for the link, Sammy. Thanks also for the book recommendation Bruce, I'll see if I can find it tonight after work. I deal best with an explanation of the fundamentals, then examples with solutions. Does that book have any of that? Either way, I'll probably grab it.

[BruceZ]

[ QUOTE ]
I deal best with an explanation of the fundamentals, then examples with solutions. Does that book have any of that?

[/ QUOTE ]

It has examples with solutions. It's especially good if you are reviewing stuff you learned before.