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#1 2013-03-29 11:24:48

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

help

hi

If I have the 1 circle, 3 triangles and two hexagons and they're in a bag and pick them two times with return what is the probability of getting exactly one hexagon ?

I get 3/9 but the answer is 4/9....

help pls thanks

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#2 2013-03-29 11:33:03

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

Hi;

4 / 9 is the correct answer.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#3 2013-03-29 11:33:57

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

Could you explain me how you did it ? I get 12/36 and not 16/36....

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#4 2013-03-29 11:37:08

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

Hi;

For school problems you should be using the simplest ideas, especially when you are stuck. Did you draw a tree?


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#5 2013-03-29 11:40:05

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

yes. and what do you mean by simplest ideas ?

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#6 2013-03-29 11:44:28

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

You always have to get an answer. One way, or the other.

Let me show you how to draw the tree without drawing it:

This is your set of possibilities,

now the triangles and the circle we are not interested in so we give them the generic label of "other." Your set becomes,

the tree looks like this,

oh
ho
oo
hh

do you follow?


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#7 2013-03-29 11:47:55

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

ok...

explain this
oh
ho
oo
hh

Last edited by Al-Allo (2013-03-29 11:48:30)

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#8 2013-03-29 11:50:59

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

Hi;

oh = ( 4 / 6 ) ( 2 / 6 )
ho = ( 2 / 6 ) ( 4 / 6 )

oo = who cares
hh = who cares

Can you finish that?


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#9 2013-03-29 11:54:49

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

it gives 16/36

but i still don't understand the logic behind it sad  how did you get those numbers ?ty

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#10 2013-03-29 11:59:58

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

ho means I drew a hexagon and then something else. The probability of drawing a h is 2 / 6 because there are 2 of them out of the total 6. Then I draw an o, the probability is ( 4 / 6 ) because there are 4 of them out of 6. Same logic for oh.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#11 2013-03-29 12:09:30

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

i think im gonna re read the problem... im not sure of even understanding what they want ..ty for your help

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#12 2013-03-29 12:13:09

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

If you are not sure of the problem then please just copy it over here.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#13 2013-03-29 12:22:11

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

Here :

An aleatory experience consists of turning an arrow on a roulette two times. (3 triangles, 1 circle, and two hexagon)

Question : What is the probability of obtaining exactly one haxagon.

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#14 2013-03-29 12:34:57

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

The question is the same as the one you posted in post #1. The answer and logic are the same, 4 / 9. I can draw a tree if it will help.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#15 2013-03-29 12:37:46

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

Yes, please. !

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#16 2013-03-29 12:57:45

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

Here is the full tree do you know what to do from here? Pay no attention to the numbers after the words circle triangle or hexagon.

View Image: 2013-03-29_174835.gif

In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#17 2013-03-29 13:08:48

Al-Allo
Member
Registered: 2012-08-23
Posts: 294

Re: help

anyway, ill go through what you posted tomorrow, i dont have the energy tonight to think about it. thanks for your efforts to help.*curiously, when you get stuck on problems, how do you operate to solve them? any principles,etc. ?

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#18 2013-03-29 13:19:05

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 89,150

Re: help

For probability and combinatorics when stuck I do it the hard way. No calculations, draw trees or count them all by hand.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

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