Started By
Message

re: Solve this OT

Posted on 7/23/18 at 2:49 pm to
Posted by LSUBoo
Knoxville, TN
Member since Mar 2006
104456 posts
Posted on 7/23/18 at 2:49 pm to
Well, the next ball is either gold or silver... that's two possible color outcomes.


Just happens that there are two gold balls potentially in play and only one silver.
Posted by PearlJam
NotBeardEaves
Member since Aug 2014
13908 posts
Posted on 7/23/18 at 2:49 pm to
quote:

While that is true, the ball can only be gold or silver, it does not mean there is a 50%chance the ball you choose will be silver.

While the outcome will only be gold or silver, the odds of the gold outcome are 2/3.
I have said that repeatedly.
Posted by CptRusty
Basket of Deplorables
Member since Aug 2011
11740 posts
Posted on 7/23/18 at 2:52 pm to
quote:

Just happens that there are two gold balls potentially in play and only one silver.




each of them representing a unique statistical outcome.

That's why the answer is 2/3.
Posted by PearlJam
NotBeardEaves
Member since Aug 2014
13908 posts
Posted on 7/23/18 at 2:56 pm to
Once you picked the first ball and you learn it is gold, you know it is 2 times more likely that you picked the gold ball from a box with 2 gold options than from the box with 1 gold option. However, at that point, when you take the second ball out of the box, only 2 options remain. It is either the other gold ball or a silver ball.
Posted by UpToPar
Baton Rouge
Member since Sep 2008
23095 posts
Posted on 7/23/18 at 2:56 pm to
quote:

I am trying to think of a way using combinations:

Eliminating the obvious now [S,S] and adding the fact you have successfully chosen a G ball, You are left 3 choose 1 combinations (3 comb) in two boxes: [G1,G2], [G3,S].

The combinations are:

G1,G2
G2,G1
G3,S

2 out of the 3 combinations (67%) grant you a successful outcome.


That's not why the answer is 67%. You can't eliminate the S,S box and not also eliminate either the G1,G2 or the G2,G1 combination after picking the first gold ball. One of those combinations is already eliminated.

The reason the answer is 67% is due, entirely, to the fact that IF your first pick was a gold ball then its more likely you have already selected the box with the 2 gold balls.
Posted by PearlJam
NotBeardEaves
Member since Aug 2014
13908 posts
Posted on 7/23/18 at 2:57 pm to
Thank you.
Posted by slackster
Houston
Member since Mar 2009
91873 posts
Posted on 7/23/18 at 2:58 pm to
quote:

Uhhh... It is either silver or gold. They aren't all in the same box and a gold ball has been eliminated. It's either the gold ball that was in the box with a silver ball or it is one of the 2 gold balls that were once together.


Your explanation here says there are 3 possible outcomes, yet you argue otherwise.

Knowing we chose a gold ball leaves us with 2 possible BOXES, those boxes have 4 balls in them. We've seen one of the balls. There are 3 balls we haven't seen, ergo, 3 possible outcomes.
Posted by Ingeniero
Baton Rouge
Member since Dec 2013
23601 posts
Posted on 7/23/18 at 2:58 pm to
Let's do it like this. Anyone who doubts the 67% answer, answer these questions for me:

1. Before removing any balls, what is the likelihood you choose a gold ball if you're holding the GG box?

2. Same question as above, but the GS box?

3. Same as above, except now the SS box?

4. What is the likelihood you choose one of these 3 boxes at random?

Once someone answers all 4 correctly I'll show you why it's 67%
Posted by RobbBobb
Member since Feb 2007
34403 posts
Posted on 7/23/18 at 2:59 pm to
quote:

The reality of the situation is that your gold ball was one of 3 possible choices

No, No, No, No, No

Youre pulling a magicians trick by forcing a specific ball on me, but telling me I had three options to start with. I never had 3 options. By forcing the gold ball into my hand, you only allowed 2 options. It either came from the AG box or the M box. There never was the 3rd option of the AS box.

The probabilities are now strictly confined to whether I chose the AG box or the M box. It doesn't even matter what the next color I pull out is. I'm now limited to the only boxes that you allowed from the start, 2 (two). Its essentially flipping a coin at that point. It either turns up as box A or box B
Posted by PearlJam
NotBeardEaves
Member since Aug 2014
13908 posts
Posted on 7/23/18 at 2:59 pm to
quote:

Knowing we chose a gold ball leaves us with 2 possible BOXES, those boxes have 4 balls in them
no. We are stuck with the original box and one ball (a gold one) has been removed. 1 ball of unknown color remains in the 1 box.
Posted by slackster
Houston
Member since Mar 2009
91873 posts
Posted on 7/23/18 at 2:59 pm to
quote:

Well, the next ball is either gold or silver... that's two possible color outcomes.


Just happens that there are two gold balls potentially in play and only one silver.


Yes. All of this is true.

There are two possible colors remaining.

There are 3 possible balls remaining.
Posted by slackster
Houston
Member since Mar 2009
91873 posts
Posted on 7/23/18 at 3:00 pm to
quote:

no. We are stuck with the original box and one ball (a gold one) has been removed. 1 ball of unknown color remains in the 1 box.




By that logic there is only one outcome remaining - whatever ball is in the box is the only outcome it can be.
Posted by CptRusty
Basket of Deplorables
Member since Aug 2011
11740 posts
Posted on 7/23/18 at 3:01 pm to
quote:

The reason the answer is 67% is due, entirely, to the fact that IF your first pick was a gold ball then its more likely you have already selected the box with the 2 gold balls.




Explain why, and show your work.
Posted by monkeybutt
Member since Oct 2015
4584 posts
Posted on 7/23/18 at 3:01 pm to
quote:

No, No, No, No, No

Youre pulling a magicians trick by forcing a specific ball on me, but telling me I had three options to start with. I never had 3 options. By forcing the gold ball into my hand, you only allowed 2 options. It either came from the AG box or the M box. There never was the 3rd option of the AS box.

The probabilities are now strictly confined to whether I chose the AG box or the M box. It doesn't even matter what the next color I pull out is. I'm now limited to the only boxes that you allowed from the start, 2 (two). Its essentially flipping a coin at that point. It either turns up as box A or box B



This was run with a computer program that was run over a million times with the OP's scenario. It's been posted multiple times. The answer is 67%.
Posted by CptRusty
Basket of Deplorables
Member since Aug 2011
11740 posts
Posted on 7/23/18 at 3:02 pm to
quote:

If you had a box with 3 gold balls, and another box with 1 gold ball and two silvers, what are the odds of pulling a second gold ball from the same box if your first pull resulted in gold. Once you can answer that, you will understand why it is important to consider each ball individually.


If you understand why the answer is 2/3 then solve that for me. Show your work.
Posted by slackster
Houston
Member since Mar 2009
91873 posts
Posted on 7/23/18 at 3:02 pm to
quote:

Youre pulling a magicians trick by forcing a specific ball on me, but telling me I had three options to start with. I never had 3 options. By forcing the gold ball into my hand, you only allowed 2 options. It either came from the AG box or the M box. There never was the 3rd option of the AS box.



By forcing the gold ball into your hand I left you with two possible boxes. If you can't understand that your chances of having the all gold box are twice as good as having the half and half box, there is no point in discussing this any further.
Posted by PearlJam
NotBeardEaves
Member since Aug 2014
13908 posts
Posted on 7/23/18 at 3:02 pm to
quote:

By that logic there is only one outcome remaining - whatever ball is in the box is the only outcome it can be
well, we don't know which box we have, so it could be a gold ball left or it could be a silver. But we know when we pulled the first gold ball out, it was twice as likely to come from the box with 2 gold balls than from the box with only 1 gold ball.
Posted by ell_13
Member since Apr 2013
88451 posts
Posted on 7/23/18 at 3:03 pm to
Hey y'all... what if there were 4 boxes with:

GGG, GGS, GSS, SSS???


Posted by slackster
Houston
Member since Mar 2009
91873 posts
Posted on 7/23/18 at 3:05 pm to
quote:

Hey y'all... what if there were 4 boxes with:

GGG, GGS, GSS, SSS???



Assuming we pulled a gold ball, the chance of the next ball being gold is 80%.
This post was edited on 7/23/18 at 3:06 pm
Posted by UpToPar
Baton Rouge
Member since Sep 2008
23095 posts
Posted on 7/23/18 at 3:07 pm to
quote:

Explain why, and show your work.


If you reach into one of the three boxes and pull out a ball and it is gold, it had to come from 1 of the 2 boxes with a gold ball in it. Between those two boxes, one has 2 gold balls and the other has a single gold ball. Therefore, you are twice as likely to have selected a ball from the box with 2 gold balls. So, there is a 66.67% chance you selected the box with 2 gold balls and a 33.33% chance you selected the box with a single gold ball.

Once the first gold ball has been selected, you're next ball pulled with either be one of two possible outcomes: silver (33.33% chance) or gold (66.67% chance)
Jump to page
Page First 18 19 20 21 22 ... 39
Jump to page
first pageprev pagePage 20 of 39Next pagelast page

Back to top
logoFollow TigerDroppings for LSU Football News
Follow us on X, Facebook and Instagram to get the latest updates on LSU Football and Recruiting.

FacebookXInstagram