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  •  » Probability of Independent Events With 55% Magical Coin

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Topic review (newest first)

bobbym
2013-02-01 18:35:18

Hi;

This forum is a very good place for you to learn and share mathematics.

I like the idea that you try to use computer math to learn about math. You will only have to use half your wits as I do to succeed.

nflguy
2013-02-01 09:02:53

No programmer but I know HTML and dabble in sql server and I catch on quick to things especially topics that intrigue me.  I am the type of person that will use the excel functions for efficiency but I want to be able to know how to do it just for the knowledge.  Hell I was playing around taking quizzes last night on your site just for the fun on it.

I was always good at math in school but I dropped out before my junior year to start working so I am pretty sure I didn't learn this.  I kick myself now because the things I am interested in now math, science, history are all things I didn't pay much attention in school.  This may sound silly to some but I actually look forward to my kids bringing home school work asking for help because I want to relearn everything.  Anyway I really appreciate the help and the thorough explanation.

BTW I did find the formula on excel for those future readers that want to check their work in excel
=BINOMDIST(2,4,0.55, FALSE)

2 is successes
4 is trials
.55 is probability
true or false is for if probability is cumulative.

bobbym
2013-02-01 08:36:40

Then lets put it all together:



yes understand it all

Are you a programmer because they are much quicker than math types when it comes to understanding math!

nflguy
2013-02-01 08:30:42

yes understand it all

bobbym
2013-02-01 08:23:41

One piece at a time:







which has a formula for it



so



which is



Okay to here?

nflguy
2013-02-01 08:14:55

yes

bobbym
2013-02-01 08:11:24

Let's go back to that magical formula:



and do one. Let's say you wanted just 2 heads out of 4 tosses. We know that n is the number of heads.



Do you follow the plugging in of 2 into the formula?

nflguy
2013-02-01 08:07:09

got it

bobbym
2013-02-01 08:05:27

Mathematicians are real big on two things, jargon and notation. They figure that way no one knows what they are talking about and that is the way they like it.

4! pronounced 4 factorial is shorthand for 4 x 3 x 2 x 1.

3! is 3 x 2 x 1

8! is 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1

Okay?

nflguy
2013-02-01 08:01:00

start right there

bobbym
2013-02-01 08:00:16



Do you know what a factorial is? For instance is 4! familiar to you or should I start right there?

nflguy
2013-02-01 07:58:14

yes I understand so far

bobbym
2013-02-01 07:53:56

That little dot in front means multiplication.

(.55)^n means raise .55 to the power of the number of heads.



Is an nCr or a binomial coefficient. The definition depends on a factorial, do you follow so far?

nflguy
2013-02-01 07:50:55



I dont know what cdot is and how to do the 4 over the n.  Its been about 20 years since I learned this stuff and my memory just isn't what it used to be. sad

bobbym
2013-02-01 07:44:13

You can use that formula for hand calculation. What part of it do you not understand?

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