Math Is Fun Forum

Prakash Panneer

Member

Registered: 2006-06-01

Posts: 110

One more problem on Probability

Problem:

6  marbles( Green, Blue , Red, Yellow, Orange and Purple) in a bag and throughly mixing them up and with replacement  find the probability of getting  Green and Blue?

Thanks in Advance

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Letter, number, arts and science
of living kinds, both are the eyes.

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: One more problem on Probability

I'm guessing on exactly two picks?

The first pick, you may either pick a green or a blue marble and claim success.  Thus, the chance is 2/6.

The second pick, you must be exactly the color that you didn't pick on the first time.  Thus, the chance is now 1/6, since there is replacement.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: One more problem on Probability

So the chance of getting green then blue combined with the chance of getting blue and then green is (2/6)(1/6) = 1/18.
The chance of getting just green then blue is 1/36.
And blue then green is 1/36.

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George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: One more problem on Probability

How do you pick?

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X'(y-Xβ)=0

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

Re: One more problem on Probability

1/18

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Numbers are the essence of the Universe

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: One more problem on Probability

I assumed randomly, George.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: One more problem on Probability

Randomly pick two, not putting back?

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X'(y-Xβ)=0

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: One more problem on Probability

Then it should be:

If you pick a ball, record its color, then put it back before picking another time, the result would be 1/36, regarding the sequence.

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X'(y-Xβ)=0

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: One more problem on Probability

in a bag and throughly mixing them up and with replacement

So yes to putting them back.

Your 1/36 number, I believe you are calculating the probability of picking a green and then picking a blue.  However, the question stated is just picking a green and a blue, with replacement.  So you could pick a blue and then a green as well.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

George,Y

Member

Registered: 2006-03-12

Posts: 1,379

Re: One more problem on Probability

Uh, with displacement, then it would be 1/18

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X'(y-Xβ)=0

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: One more problem on Probability

If you meant with replacement, I agree.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."