Hey, this is Presh Talwalkar. Surveys have found that eighty percent of people get this problem wrong. While you are thinking about it I am going to present a similar problem. Give these problems a try and when you’re ready keep watching the video for the solution. Many people think that the answer to the first problem is C) Cannot Be Determined. However, we need to work through the logical possibilities. While we do not know Bob’s marital status we should work out each case to see if the condition is met. One case is that Bob is married. In that case, he is a married person whose looking at Charlie, who is unmarried. So if Bob is married The condition that a married person is looking at an unmarried person is true. What would happen if Bob is not married? In that case, Alice, whose married, is looking at Bob, whose unmarried. So in this case too, it would be true that a married person is looking at an unmarried person. So the correct answer choice is A) Yes Although we don’t know which married person is looking at an unmarried person We know that some married person is looking at an unmarried person. Now let’s tackle the next problem! Imagine that we draw the three socks in order. Now, it could be the case that the first two socks you pull are both black or they’re both white. In that case, you would already have a matching pair of socks before you even pull the third sock. Now what would happen if that’s not the case? Well, then the first two socks would have to be different colors. You would have to have one white and one black sock. Then, when you pull the third sock, It would have to be either a white sock –matching the white sock you already have– or a black sock–matching the black sock you already have. The third sock must match one of the socks you already have. Therefor, in either case, you will always be holding a matching pair of socks. Did you figure out these problems? Thanks for watching this video! Please subscribe to my channel. I make videos on math and game theory. You can catch me on my blog, MindYourDecisions which you can follow on Facebook, Google+, Patreon. You can catch me on social media @preshtalwalkar And if you liked this video, please check out my books. There are links in the video description.

For the 1st problem, it cannot be determined for 2 reasons:-We don't know if Bob is married or not-If we select yes, then Bob may be unmarried which is false, if we select no, then we will found that Alice is married (obvious).

Even though the two problems are different.

Im 9 and i got them both right

You are cancer

___The answer to the Alice question is C. WTF are pushing?

what if I pull 3 white socks

I do like that you realize these problems are logic problems, and title then aptly. No math needed.

There's too much blurring of the lines between logic and math as it is nowadays. Logic can be done without math, but math requires logic.

The supposed answer to this question is actually INCORRECT. Here's why. There is nothing in the question that states or even implies that Bob is a person – Bob could be a Golden Retriever. If Alice is looking at Bob the dog and Bob the dog is looking at Charlie then a married person ISN'T looking at an unmarried person. However, there is nothing in the question to say that Bob is a dog, it is merely a possibility within the terms of the question. If Bob was a person then the answer would be A) Yes. As Bob's personhood cannot be ascertained then the answer must be C) Cannot be determined. 🐶

What if u had three black socks??

Damn, u got me!

For the second problem, what if you pick up 3 socks of the same color, it really cannot be determined

This was so ez how can 80% get it wrong

Bob is unmarried. So Alice – married – is looking at him – an unmarried person.

Bob is married. So he – married – is looking at Charlie – an unmarried person.

So, the answer is YES, no matter Bob is married or not.

Yes

Question 2 assumes without stating that socks of the same colour are a matching whereas in reality you could socks with varying sizes thus making it undetermined.

I knew it was yes

But what if you draw three black or white socks at once? Or did I miss something?

I got the first one right after some thinking because I'm a genius. I got the second one wrong because I'm not smart. 🙁

i say its still C….. wht if bob is a dog

What if you draw 3 socks which are all in same color ^o^~(3 black or 3 white? I think there’s possibility because you have to close your eyes when you pull them out ^^

the answer is C. Cannot be determined. Nothing in the question specifies if Bob and Charlie are Persons. Alice is looking at a married person, Bob, who is looking at their dog, Charlie.

sadly, I failed miserably

Yes because bob is always in Alice's sight and Alice married. If bob is unmarried than that satisfies it.

If bob is married than he would be looking at Charlie who is unmarried which will satisfy it

yes because if bob is married he looks at charlieso yes and in unmarried alice looks at him

Is Charlie male or female?

That was easy. Both of them.

B.no

Alice is looking at Bob

My 2 year old figured out the 1st one.

The second one seems simple on the surface but it's actually not. The socks are not a matching pair unless they came out of the same package connected together during purchase in which case you would not necessarily have a matching pair if you only through 3. End of story

Too easy

You can also have 3 same color socks

Let me guess and hope

Alice (A) is looking at Bob (B)

B is looking at Charlie (C)

And A is married to an idiot, While C is

forever aloneSo A>B>C

And it could mean B was married to A

(Unless B is broke)So Am>Bm>Cu

Since B is married but C isn't, And there is a part "B>C"

The answer is Alice

You'd get it is A

Oh there is another part,

10b+10w-(bx+wy)

The possibility for a pair of socks is equal to (100/20)/2

(I may be wrong so stop hating)So that results to 2.5%

And let us say you get a fidget spinner

(Yeah I am horrible)And a paper marked with numbers

The fidget spinner shall spin for like 60 seconds

And it has a 2.5% chance of reaching anything<2.5

It got 69

Yeah you may be holding a pair of socks IDK

I got them all right!

Yes

Yes

The first one did confuse me at first, but the sock problem was pretty easy to comprehend😊. Tysm for making these fun videos that challenge ourselves

My guesses:

1 no

2 yes

I failed…add me to the %

What is if i take 3 right feet socks in second question?

Lol the second one was just so obvious I thought there was gonna be like some special trick like the first one but no, I got it right, instantly…

The first problem, I just thought that since Alice is looking at Bob, she’s married to Bob, so the answer must be A. Lol

The answer is yes… No matter whether Bob is married or unmarried , there will always be one married person looking at an unmarried one..

For the third one, this was my thought process:

If you draw three of the same color socks, then you won't have a pair.

Looks at the problem againQuestions thought processes and writes it downHow could anybody get these wrong?

How is this even a puzzle?

When I asked my son both the questions he said that 'yes' is the correct answer for both the problems.

My son has solved many of Presh's problems correctly in spite of being a student of class 7.

The second problem is obvious.If a pair of socks are chosen they can be bb ww bw wb so the

It is obvious.If a pair is drawn they can be ww bb wb bw so the third draw must match one

one or other of the latter.

The answer to the second problem is wrong, you aren't holding a pair of socks. You are holding three socks, which isn't a pair.

Mind blown

I was confused, bcs i though That Charlie was Bob :v Anyway i chose A)

666k views

666K views (I'm always making comments like these, and that's basically the only thing I do on YouTube other than listen to music XD)

in this the key person is Bob, if he is married the answer is yes bcs he looks at Charlie, if he is not then also the answer is yes bcs Alice looks at him. so in both cases the answer is yes!

I’m a 10 year old and I managed to solve it.

Kind of scary that 80% could fail this problem…

Yay I got one right for once

It’s not possible to determine Bob’s relationship status since he is not trustworthy on such matters. Whether or not he is married depends upon who’s asking. It’s also possible that Bob is/was going through a divorce at the time that he was asked, and doesn’t himself fully know for a certainty what his relationship status is.

These could explain why Bob’s relationship status is not give and why the question is being asked in the first place.

At any rate, the answer is yes. As Alice is married and Charlie is not. But is Alice the only married person or is Charlie the only unmarried person? Bob must be both married and unmarried st the same time.

I got this one in just 3 seconds. Easy one 👍

What if all of them are married to a person outside the question?

Great explanation!

Currently at 0:27 in the video, I answer "Yes".

This is because if Bob is married, then he is looking at Charlie (who is unmarried) and that satisfies the condition of the problem. On the flipside, if Bob is unmarried, then Alice (who is married) is looking at Bob (who is unmarried), and that also satisfies the condition of the problem.

So logically, the answer to this question is always "Yes" with full certainty.

Thank you Digital Circuits I for teaching me boolean algebra.

I shall now watch the rest of the video to see if I'm mistaken. ( ͡° ͜ʖ ͡°)

Yes.

And yes.

C'mon, this one was easy…

Lets see…

A? Because substitute bob for married or unmarried and its true

You told us to draw socks. It can not be determined if we are holding a matched pair of socks. As you know in logic problems, words matter!

First is little tough I figured it out after some thinking but second is extremely easy solved it at once.

I GOT IT RIGHT

Socks can be the same colour but not the same pair. Like if you grabbed one white sock that was an ankle sock and one white sock that was a knee-high sock, they'd be two totally different pairs of socks. You should have made it more clear by saying "if you grab the same colour, then they are considered to be matching".

The answer is "YES", absolutely.

Two options:

1) Bob is not married. Therefore Alice (married) looks at Bob (not married) – answer is YES.

2) Bob is married. Therefore Bob (married) looks at Charlie (not married) – answer is YES.

Either way, the answer comes out YES.

But is Bob wearing matching socks?

Probably a more interesting, but still easy, question would be whether you have pulled a sock of each color.

Transposed to shoes, mathematically speaking, a true pair would be two left or two right ones 🙂

found your channel… Now I'm in love with solving these probs and testing my reasoning skills… u may see now a series of notification of my comments as I can see other comments are 1-2 years old… haha it's really interesting 😀

Actually, for constructivists the answer to the first problem is C, the reason being that they deny 'the excluded middle' that states "either something is true or it is false" which in this case would be "either Bob is married or not". In the second problem though, everything is defined, and the answer is therefore A independent of the school of thought.

3 is not a pair.

What the hell is this? Harder ones

They all are getting married this December.

yes

Yes, these questions are not precise enough from a philosopher's point of view. Generally, in language, when we are holding three socks, we are NOT holding a "matching pair." Yes, it's true we are holding AT LEAST two socks (because we are holding three) but we normally reserve the use of the word "pair" for when we ONLY have a pair of something. If we ask someone for a "pair of socks," we are not pleased when they hand us three, even if a pair helps comprise the three. As to the married people, as has been pointed out below, the names "Bob" etc. could belong to a dog, or a ship. And if you want to deal with humans only, do we really consider priests, monks, etc. as "unmarried"? This suggests that they HAPPEN to be unmarried, when they have CHOSEN to be unmarried. It's like saying people HAPPEN NOT to be priests. It worries the point. Puzzle makers need in general to do a better job to confine answers to one – and only one – possible result.

I’m just an unmarried sock…

Got them both right as used to do logic puzzles all the while as a kid with my Mom however the second question is one of those you could end up seeing on FaceBook with no 'correct' answer. The question specifically says "Are you holding a matching pair of socks?" to which you could also answer no as you've got 3 socks so not a pair. I wish the wording on these sorts of questions were better as unfortunately there are people out there that will put them on Facebook as a test and then make fun of people no matter what they answer.

Erm….. What if Bob is divorced. Neither married nor Unmarried.

2nd was very bad

Toooooo simple

You didn't say the socks are all the same size? Therefore cannot be determined?

Apply the same principle to a problem involving N people. Prove that a married person is always looking at an unmarried person.

These problems always work with assumptions. However , on the second problem you assumed only one possibility which it was to take the socks in order. If you take the socks not in order it will not work

Serious ego boost after me figuring the first one out

I’m so proud of myself

But if you take a white sock and two black but both right or both left…the second could be indeterminated idn

really cool video, i've confused all my family with these lol

You do not have a matching PAIR of socks you have three socks not 2

I feel so proud of myself after finding the answer for both the questions correctly !! I'm a god at fortnite

Feeling so smart😎

Superposition,except their currently being observed.

It's C cannot be determined because Alice, Bob and Charlie could be animals.

Q1 ans will be yes beacause Bob may be married or may not if married then 1)yes bob is looking unmarried person

2)if unmarried then alice(maried)looking bob(unmarried)

First one was easy enough. Didn’t understand the second lol

Yes or A for both questions , since if Bob is married then Alice is looking at a married person, Bob and therefore Bob (married) is looking at an unmarried person Charlie. however ,if Bob is unmarried then Alice who is married is looking at an unmarried person Bob. A person is either married or unmarried.

For the socks question one must pick a pair of socks that is either two single white socks (or a pair) or two single black socks (or pair), so A is the answer also for the sock question as one has to either pick 3 white socks or 3 black socks, or 2 white and 1 black or 2 black and 1 white, just four (4) possible outcomes. so A is correct for both questions

just pretend first bob is married, and then pretend again that he is unmarried and you get the answer

It seems so difficult at first. But if we just break down the question or explain it briefly to ourself,we can easily get it. Thanks 😊.

What if Alice is married to some other person and Bob and Charles are married?

Then answer will be NO?