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## #126 2012-11-10 04:52:25

bobbym

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### Re: Expectation

The expected value is 1/probability is it not?

The matrix when computed should be 13.7

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #127 2012-11-10 05:07:04

anonimnystefy
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### Re: Expectation

http://www.wolframalpha.com/input/?t=cr … 5%2F6))%5D

How is the expected value 1/probability?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #128 2012-11-10 05:17:13

bobbym

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### Re: Expectation

Hi;

You did not enter the problem correctly
Matrix Inverse( IdentityMatrix[6] -  {{0,1,0,0,0,0 }, {0,1/6,5/6,0,0,0} ,{ 0,0,1/3,2/3,0,0} ,{ 0,0,0,1/2,1/2,0} ,{ 0,0,0,0,2/3,1/3} , {0,0,0,0,0,5/6 }}).{{1},{1},{1},{1},{1},{1}} gives the right result.

If the probability is 1 / 6 of something happening then we expect it to happen once in 6 times.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #129 2012-11-10 05:27:35

anonimnystefy
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### Re: Expectation

My result is correct. I just didn't sum the first row.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #130 2012-11-10 05:42:45

bobbym

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### Re: Expectation

When I entered yours it says the trace is 14.7. The trace is the sum of the diagonal elements. It may or may not be correct.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #131 2012-11-10 05:47:32

anonimnystefy
Real Member

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### Re: Expectation

The trace and the sum of the first row are the same for that matrix.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #132 2012-11-10 06:09:10

bobbym

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### Re: Expectation

Yes, but are you sure that will always be the case?

This way spits the answer out in a form that is easy to understand.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #133 2012-11-10 07:19:59

anonimnystefy
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### Re: Expectation

No, I sum the first row. WA is the one who thinks you need the trace.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #134 2012-11-10 07:30:46

bobbym

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### Re: Expectation

Hi;

For one thing he did not interpret the identitymatrisx command correctly. For another the inverse was not calculated...

I would do it the way I showed in post#128.

Taking a little break.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #135 2012-11-10 07:45:29

anonimnystefy
Real Member

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### Re: Expectation

That is not the same result I am getting when I press the link.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #136 2012-11-10 08:19:46

bobbym

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### Re: Expectation

Supposing others get my result? Isn't my way more reliable, since we are both getting the same answer. Also, my syntax is much closer to the package's syntax.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #137 2012-11-10 08:59:40

anonimnystefy
Real Member

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### Re: Expectation

You just had multiplication by the vector (1,1,1,1,1,1) and I did the multiplication by hand. It is the same method.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #138 2012-11-10 09:23:12

bobbym

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### Re: Expectation

Hi;

I am talking about the syntax of the commands.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #139 2012-11-11 10:07:21

anonimnystefy
Real Member

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### Re: Expectation

New problems?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #140 2012-11-11 10:51:12

bobbym

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### Re: Expectation

A deck of cards are dealt out in a circle. What is the expected number of pairs of adjacent cards which are both black?

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #141 2012-11-11 10:57:08

anonimnystefy
Real Member

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### Re: Expectation

A standard French deck?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #142 2012-11-11 11:31:46

bobbym

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### Re: Expectation

Hi;

It is a regular deck of playing cards.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #143 2012-11-11 11:39:58

anonimnystefy
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### Re: Expectation

Okay.

What do you get as the answer for decks of 4 and 6 cards (half of which are black)?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #144 2012-11-11 11:46:15

bobbym

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### Re: Expectation

E(4 card deck) = 2 / 3

E(6 card deck) = 6 / 5

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #145 2012-11-11 11:58:07

anonimnystefy
Real Member

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### Re: Expectation

And E(8)?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #146 2012-11-11 12:08:29

bobbym

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### Re: Expectation

E(8 card deck) = 12 / 7

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #147 2012-11-19 11:29:44

anonimnystefy
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### Re: Expectation

I haven't been able to find a solution...

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #148 2012-11-19 11:31:49

bobbym

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### Re: Expectation

Hi;

Okay, I can give the answer if you want it.

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.

## #149 2012-11-19 11:33:15

anonimnystefy
Real Member

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### Re: Expectation

I'd rather get a method than an answer, but either is okay...

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón

## #150 2012-11-19 11:43:51

bobbym

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### Re: Expectation

Hi;

I'd rather get a method than an answer,

Hmmmm. You should already have the answer or darn close to one. Have you forgotten how we work?

In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.