logic puzzle thread originelli's pizza

>>34171290
Like 75% or something. Higher than 50% read about the goat doors. It's been a while

>>34171290
1/2 why would people be confused by this?

>>34171365
Correct

originolium

I remember doing this out before and it being like 1/3 but I can't see why it wouldn't be 1/2.

>>34171433
You have a gold ball in your hand.

>>34171290
It's 2/3. There's double the chance you've picked from the left box given the information.

>>34171483
Wait I misread it, this version of it has been modified so that it IS 50%, since ONLY the selection of the box matters and it occurs first.

File: multipliation_rule[1].gif (292B, 160x18px) Image search: [Google]

292B, 160x18px

>>34171290
Pic related.

A = P(Gold)
B = P(Gold again)

>>34171365
>>34171397
>>34171511
What if I added another gold ball to box 1 and another silver ball to box 2? Is it still just as likely you chose box 2? What if I added 1000 balls to each in the same way?

Think about that and consider your answer.

>>34171433
Because it's the boxes that matter, not the balls.

The left box could have infinite balls for all you care, you still need to pick between the two boxes anyway.

Only the first draw calculates all the balls in question, but since it's given information we're getting a golden ball 100% of the time they stop mattering.

>>34171569
you already picked a golden ball, it doesn't matter what the probabilities of that happening, it just asks the probability of the next ball being golden

and you either picked a box with only golden balls remaining or a box with no golden balls remaining, it's 50/50

These thread always end up in flamewar because people love to question pure maths

Is there a reason baye's Formula here >>34171566 would not work?

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>>34171623
Pic related. It's been a while since statistics class.

So wait the answer if 50% right?

Is this the correct logic: (1/2 x 1) + (1/2 x 0)

???

Simple solution: The ball you are holding belongs into box 1 with a probability of 2/3 and into box 2 with a probability of 1/3. Consequently the chance to pick another gold ball is 2/3 since you are guaranteed to pull it/not pull it if you first got box1/box2.

>>34171606
So you're saying

that with box 1 containing a sea of gold balls

and box 2 containing a sea of silver balls with a single gold

that a gold ball you picked at absolute random has the same likelihood of being from either box?

>>34171290
This is the kind of thread where you see just how dumb most of the people on here are

>>34171659
This is the formal approach


Just think of it like this: there's 4 options that you can draw, each have 1/4 chance: gold box 1, gold box 1, gold box 2, silver box 2

We know it's not the last option

So since 2/3 of these options (which all had the same probability) have the ball drawn from box 1, that's the chance of drawing gold again

What confuses people is that they think the chances are equal because both boxes have a gold ball in it.

Think of it like that: say both boxes had 1000 balls in it. One of them had only golden balls, the other 1 golden and 999 silver ones. If you draw a ball at random from a bix and it turns out gold, you'll be pretty sure it's from the box with only gold balls

>>34171775
That is a completely different question.

https://en.wikipedia.org/wiki/Bertrand's_box_paradox

np

i can see through the box, its up to me on which ball i grab

You grab a gold ball. Here are all the ways you could have got to that point.

>you grabbed gold ball 1
>you grabbed gold ball 2
>you grabbed gold ball 3, from the mixed box

You only know you grabbed a gold ball. You don't know which one it is, but there was only three possibilities. Given this, there's also only three possible outcomes from this point

>you grab gold ball 2
>you grab gold ball 1
>you grab the silver ball
Two of those three outcomes result in a gold ball. 2/3 chance.

As a guy that never learned stats or graduated high school, I need some help with this

Just going by balls, it's obvious that it's 2/3, but when you think about picking the boxes, the chances of picking either box are 50/50, so some might say it's 50/50 for the 2nd gold ball

But then, the case where you pick the silver ball is eliminated, so even though you have a 50/50 chance of picking either box, the box on the left is "weighted" more.

Was I even close?

>>34171793
maybe you should read what you replied to again because that's what I asked

>>34172123
The left box has two chances to grab a gold ball on the second draw. The right box only has one.

>>34172145
Rather the right box has none.

>>34171757
righty-o

are you a math major or something?

What if whenever you pick the right box, you are automatically handed the gold ball, every single time?

>>34171290
P(second gold|first gold) = P(second AND first gold)/P(first gold) = (1/2)/(3/4) = 2/3

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>there are people here trying to make it sound like it's not 50/50
It's funny, because trying to make themselves sound smarter just makes them look dumber.

yeah, i thought it was 50% too. But i was wrong...it's 2/3

this guy explained it well >>34172063

>>34172537
Listen here, man, we get guys like you every thread

Get two boxes, three quarters and a dime and try for yourself. Count how many times out of the ones you picked a quarter first (and ONLY those times) you picked a quarter again. I guarantee you it will be about 66% of them.

>>34172614
I got 64%. Fuck off nigger

THAT FUCKING GOAT

it's 66% btw

you grab gold ball
there are gold in both boxes so you still don't know which box is which
second ball can be either gold or silver
only those two options are possible
50/50

>>34173054
There's three gold balls to grab, nigger.

>>34173180
but you take twice from the same box
so second time there is only one ball left
either silver or gold one no other options there

>>34173236
You don't know what ball you grabbed, you just grabbed a golden ball. Since you already drew a gold ball, that now means there's two ways to grab another gold ball on the second draw, and one way to grab a silver ball.

>>34173236
That's just it. Nobody in this thread is taking into account that you're drawing from the same box twice.

>>34173374
thank you
finally someone understands

>>34173278
kys stupid nigger

>>34173374
You don't have to. There's two different ways to initially draw from box 1, and only one way to draw from box 2. Since you must draw a gold ball on the first try, that only gives three possible outcomes.

>Draw gold ball 1, then draw gold ball 2
>Draw gold ball 2, then draw gold ball 1
>Draw gold ball 3, then draw the silver ball

Only two out of those three result in a gold ball on the second draw. 2/3 = .667 =66%

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solved this ages ago

2/3. Learn stats, lads.

>>34173567
>Learn stats you dumbo

>>34171290

The thing that nobody is pointing out here:

The existence of the boxes is completely irrelevant to this problem. If you pick the box randomly and then pick the ball randomly, then guess what: the box thing only existed to help you pick a ball randomly.

If the ball you picked allowed you to deduce something about which set you had picked it from, you could use that information to better model the probability. It doesn't, so you can't.

It's 2/3.