Non-political Wednesday diversion-Brainteasers

[nobody 2,031]

28 minutes ago, jerryskids said:

The answer involves Bayes Theorem but I don't feel like figuring that out.  Basically we know the accuracy if you have the disease; the question is the probability you have the disease given the result.

Also put me in the 50% camp for the OP, at least how it was worded.

Base rate neglect, too.  

It's about 1 in 11 that you actually have the disease.  

This is why you always hear these stories about miracle healings.  Once you're tested positive for the disease, you're either in the true positive group (1 in 10k) or the false positive group (1 in 1000).  

Of course the drug companies don't tell you all of this stuff.

[posty 2,295]

https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

[parrot 789]

There are five bags of gold that all look identical, and each has ten gold pieces in it. One of the five bags has fake gold in it. The real gold, fake gold, and all five bags are all exactly identical in every way, except the pieces of fake gold weigh 1.1 grams, and the real gold pieces weigh 1 gram. You have a perfectly accurate digital gram scale and can use it only once. How do you determine which bag has the fake gold?

[Strike 3,934]

Honcho's question is NOT the same as EITHER of the questions answered in that video.  And those saying 33% are still wrong.

[Mike Honcho 3,999]

1 minute ago, parrot said:

There are five bags of gold that all look identical, and each has ten gold pieces in it. One of the five bags has fake gold in it. The real gold, fake gold, and all five bags are all exactly identical in every way, except the pieces of fake gold weigh 1.1 grams, and the real gold pieces weigh 1 gram. You have a perfectly accurate digital gram scale and can use it only once. How do you determine which bag has the fake gold?

The paradox has frequently stimulated a great deal of controversy.^[5] Many people argued strongly for both sides with a great deal of confidence, sometimes showing disdain for those who took the opposing view. 

Boy that is true.

[bandrus1 413]

Just now, Strike said:

Honcho's question is NOT the same as EITHER of the questions answered in that video.  And those saying 33% are still wrong.

Exactly

[Mike Honcho 3,999]

Really, how is my question that I found on a brain teaser website, not the same as those in the video or the wiki answer...or anywhere else on the internet answering this question...including Strikes own explanation?

[Strike 3,934]

Just now, Mike Honcho said:

Really, how is my question that I found on a brain teaser website, not the same as those in the video or the wiki answer...or anywhere else on the internet answering this question...including Strikes own explanation?

I dunno.   I guess you have to figure this one out on your own chief.  Or go ask a math teacher and give them the EXACT question you gave us.

 

[nobody 2,031]

7 minutes ago, parrot said:

There are five bags of gold that all look identical, and each has ten gold pieces in it. One of the five bags has fake gold in it. The real gold, fake gold, and all five bags are all exactly identical in every way, except the pieces of fake gold weigh 1.1 grams, and the real gold pieces weigh 1 gram. You have a perfectly accurate digital gram scale and can use it only once. How do you determine which bag has the fake gold?

My first instinct is to take the 10 pieces of each bag and mix them all up in a way such that the weight of a single bag would indicate which bag had the fake gold.

[Mike Honcho 3,999]

Well, at least we're not arguing about politics.   

[Strike 3,934]

Just now, Mike Honcho said:

Orange Man bad

[jerryskids 5,152]

9 minutes ago, parrot said:

There are five bags of gold that all look identical, and each has ten gold pieces in it. One of the five bags has fake gold in it. The real gold, fake gold, and all five bags are all exactly identical in every way, except the pieces of fake gold weigh 1.1 grams, and the real gold pieces weigh 1 gram. You have a perfectly accurate digital gram scale and can use it only once. How do you determine which bag has the fake gold?

I would take one coin out of the first, two out of the second, etc. and weigh them.  The amount over 15 grams tells me which bag is fake.

[Mike Honcho 3,999]

1 minute ago, jerryskids said:

I would take one coin out of the first, two out of the second, etc. and weigh them.  The amount over 15 grams tells me which bag is fake.

But we can only use the scale once, am I missing something?

[posty 2,295]

23 minutes ago, parrot said:

There are five bags of gold that all look identical, and each has ten gold pieces in it. One of the five bags has fake gold in it. The real gold, fake gold, and all five bags are all exactly identical in every way, except the pieces of fake gold weigh 1.1 grams, and the real gold pieces weigh 1 gram. You have a perfectly accurate digital gram scale and can use it only once. How do you determine which bag has the fake gold?

Take one gold piece from the first bag, two from the second bag, three from the third bag, four from the fourth bag, and five from the fifth bag. If the weight on the scale ends in .1, then you know the first bag has the fake gold. If the weight on the scale ends in .2, then the second bag has the fake gold, and so on and so forth.

[Mike Honcho 3,999]

Just now, posty said:

Take one gold piece from the first bag, two from the second bag, three from the third bag, four from the fourth bag, and five from the fifth bag. If the weight on the scale ends in .1, then you know the first bag has the fake gold. If the weight on the scale ends in .2, then the second bag has the fake gold, and so on and so forth.

Okay...I get it now.  Thanks.

[parrot 789]

6 minutes ago, Mike Honcho said:

But we can only use the scale once, am I missing something?

You weigh all the coins at once.  If you're .1 over = bag 1, .2 over = bag 2, etc.  

[Mike Honcho 3,999]

12 minutes ago, jerryskids said:

I would take one coin out of the first, two out of the second, etc. and weigh them.  The amount over 15 grams tells me which bag is fake.

So you can post the next one---bonus points if you can get people attacking each other.   

[parrot 789]

9 minutes ago, posty said:

Take one gold piece from the first bag, two from the second bag, three from the third bag, four from the fourth bag, and five from the fifth bag. If the weight on the scale ends in .1, then you know the first bag has the fake gold. If the weight on the scale ends in .2, then the second bag has the fake gold, and so on and so forth.

These are supposed to be brain teasers, not Google teasers.  

[Mike Honcho 3,999]

Just now, parrot said:

These are supposed to be brain teasers, not Google teasers.  

JK already solved it, he just copied the solution after the solve to explain it to the slower guys(me).  

I will allow it.   

[parrot 789]

5 minutes ago, Mike Honcho said:

JK already solved it, he just copied the solution after the solve to explain it to the slower guys(me).  

I will allow it.   

Fine.  Be that way.  

[MTSkiBum 1,593]

3 hours ago, Mike Honcho said:

John  and Jane are a married couple  They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.
What is the probability that the other kid is also a girl?

False information.

http://www.bbc.com/future/story/20161014-why-billionaires-have-more-sons

[jerryskids 5,152]

7 hours ago, Mike Honcho said:

But we can only use the scale once, am I missing something?

Yes.  We would have 15 coins total (1 2 3 4 5) and weigh them together.  If say bag 3 had the fake ones, the weight would be 15.3.  Bag 5, 15.5.  The key is to have a different number of coins from each bag.  Make sense?

Edit:  I've had internet problems all day, this just posted as I connected to an internet hotspot with my wife's account.  Seems like this has been resolved, sorry for the spam. 

[jerryskids 5,152]

7 hours ago, Mike Honcho said:

So you can post the next one---bonus points if you can get people attacking each other.   

Three conservatives and three liberals want to cross a river.
Three conservatives know how to row a boat.
Only one liberal knows how to row a boat, and that is because he was raised by a libertarian.
The boat can only hold two people at one time.
If there are more liberals on either side of the river at any one time, the liberals will say mean things to the conservatives.

Question: 
How do they all manage to cross the river safely?

[Mike Honcho 3,999]

46 minutes ago, jerryskids said:

Three conservatives and three liberals want to cross a river.
Three conservatives know how to row a boat.
Only one liberal knows how to row a boat, and that is because he was raised by a libertarian.
The boat can only hold two people at one time.
If there are more liberals on either side of the river at any one time, the liberals will say mean things to the conservatives.

Question: 
How do they all manage to cross the river safely?

Feels like this brainteaser is brushing right up on the line of political commentary in the non-political wednesday thread.   

[jerryskids 5,152]

46 minutes ago, Mike Honcho said:

Feels like this brainteaser is brushing right up on the line of political commentary in the non-political wednesday thread.   

It's a classic missionary and cannibal teaser, but you wanted me to get people to attack each other, so I changed the roles.