Off-Topic

[Fresh Tendrils]

re: Off-Topic

I need those Samurai Stormtroopers.

And those TMNT figures.

[slickdtc]

Off-Topic 2018

^ You may be onto something. Just tell me if this question I asked him upsets that (this is the first thing I asked him before attempting to solve it):

"Are you talking about each family having a THIRD child and you're asking if that would be a girl, or are you asking of the SECOND child that is mentioned is a girl?"

To which he said:

"It's asking about the second child, not some new third child."

However, you got me thinking about the fact that that other child could be adopted, and the family could have selected a girl at any time by that route. I might ask him if that is what it has to do with.

I’d throw out any additional questions you asked him because at that point the original question gets muddled. Your student could be getting confused as you try to break the problem down to figure it out for yourself. He shouldn’t have expounded upon the question besides clarifying/validating any part of the original question asked.

I’m fairly confident I’m correct due to the ages not being revealed for Family A but are for Family B. That seems to be the missing link. More chances of children (due to Family A being older) = higher probability of having a girl.

Let me know what the answer is!

[ImTellinTim]

re: Off-Topic

First post in 3 years. I'm actually proud of myself for remembering my login info.

What's up bitches.

Some weird people have green names.

[Blzer]

re: Off-Topic

Here was his response:

There is no third child. Period. That includes adopted children, aborted and replaced, none.

Even if family A’s children were old enough to have grandchildren those grandchildren would not count.

Then unprompted, he gave me the answer:

Spoiler

Family A. Possible children combination for Family A (younger child written first); boy-girl, boy-boy, girl-boy. Family B; girl-boy, boy-boy. Thus, Family A has a 2/3 chance, while Family B has a 1/2 chance.

Yeah, I agree with the math there. My problem was I was affixed to the idea that that child has an age regardless of what it is. I didn't consider the fact that, just as we don't assume one gender for the individual, we also don't assume one age for the individual. So that idea never even entered my head to begin with.

So it had a lot more to do with probability than I gave him credit for, and I was thinking of the problem like it wasn't a probability problem at all. Big whoops.

[WaitTilNextYear]

re: Off-Topic

I'm not buying that solution....If one of the two children in each family is definitely a boy, then each family would have boy/boy and boy/girl possibilities with everything hinging on the child of unknown gender. There is no second girl/boy state no matter who is older than whom. I don't see how either family would have "more combinations" than the other. Each family should have p=0.5 of having a girl if you consider fertilization to be a coin flip, which it basically is in the absence of extenuating genetic information.

[Blzer]

re: Off-Topic

I'm not buying that solution....If one of the two children in each family is definitely a boy, then each family would have boy/boy and boy/girl possibilities with everything hinging on the child of unknown gender. There is no second girl/boy state no matter who is older than whom. I don't see how either family would have "more combinations" than the other. Each family should have p=0.5 of having a girl if you consider fertilization to be a coin flip, which it basically is in the absence of extenuating genetic information.

I'll be honest, I've been thinking about his answer since my last post, and while I am actually wanting to give him the benefit of the doubt because of the idea behind theoretical probability, I am not convinced that this arrangement is actually a permutation that can ignore the fact that a second boy being born needs to be considered as two separate outcomes (whether born before or after). So when he has girl-boy, boy-boy, boy-girl, I actually think there should be another boy-boy outcome.

Outside of that, I take no bother in his idea regarding the different outcome scenarios. As we are left in the dark about the other child's age, there are more outcome possibilities for Family A than there are for Family B. I do think he is missing that fourth outcome though, which would even the odds again.

I'll ask him personally. I want to know the source of this riddle as well.

He's given nice riddles so far, though. I've gotten all of his other ones pretty quickly, but this one is a bit different (and rather controversial).

[l3ulvl]

re: Off-Topic

this has gone on long enough...

[Blzer]

re: Off-Topic

I hardly see it that way, but okay Blue Name.

Change the subject then... that's generally how this thread works.

[Fresh Tendrils]

re: Off-Topic

Just ignore the Bum.

[TripleCrown9]

re: Off-Topic

this has gone on long enough...

Our dear overlord has returned!

I hardly see it that way, but okay Blue Name.

Change the subject then... that's generally how this thread works.

It was a joke man.

[slickdtc]

re: Off-Topic

I'm not buying that solution....If one of the two children in each family is definitely a boy, then each family would have boy/boy and boy/girl possibilities with everything hinging on the child of unknown gender. There is no second girl/boy state no matter who is older than whom. I don't see how either family would have "more combinations" than the other. Each family should have p=0.5 of having a girl if you consider fertilization to be a coin flip, which it basically is in the absence of extenuating genetic information.

Yeah I’m not really buying Blzer’s student’s explanation either. Poorly worded and/or thought out question.

If they’re going to intentionally be ambiguous about the question, I like to think my answer makes the most sense. More chances = higher probability, at least in this context since the chance of having a boy or girl stays at 50/50.

The student threw out any answer challenging his own, and allowed only his flawed logic to fly.

If we’re going to do these types of problems, they have to be concrete. I don’t think introducing children of the original parent’s children was too off the wall to be considered, especially since girl or boy is 50/50.

[WaitTilNextYear]

re: Off-Topic

Yeah I’m not really buying Blzer’s student’s explanation either. Poorly worded and/or thought out question.

If they’re going to intentionally be ambiguous about the question, I like to think my answer makes the most sense. More chances = higher probability, at least in this context since the chance of having a boy or girl stays at 50/50.

The student threw out any answer challenging his own, and allowed only his flawed logic to fly.

If we’re going to do these types of problems, they have to be concrete. I don’t think introducing children of the original parent’s children was too off the wall to be considered, especially since girl or boy is 50/50.

The biggest problem with the construction of that particular question is it (erroneously) seemed to want age to matter really badly. When it actually has zero bearing on the probability of gender. If one is 100% male (p=0), then the other is a coin flip (p=0.5). If one coin is taped to the table as a heads and I flip a second coin to see if heads or tails, that second flip is the only unknown outcome with p=0.5. If I had taped "coin 2" to the table as heads instead and flipped coin 1, it would be no different.

The whole age and interests add-ons are the type of "extra information" I sometimes build into word problems on my homework sets to see if students can actually wade through the chaff and find the wheat.

[z Revis]

Off-Topic 2018

I don’t even understand the students answer to be honest. I have no idea where he’s getting that “math”, as Blzer called it, from. Both families have a confirmed boy, both have a 2nd child with an unknown gender. So, how are the odds of either families 2nd child different? Should be the exact same odds and if not then slick’s answer made the most sense to me.



Sent from my iPhone using Operation Sports

[ImTellinTim]

re: Off-Topic

The probability isn't about the chances of having a boy or girl. It's about the statement "that family has a girl" being true. The answer is correct in those terms and it's why probability is a mind**** when you try to study it.

4 possible outcomes of child 1-2, all equal. B-B, B-G, G-B, G-G. As everyone has correctly pointed out, they all have the same chance of happening.

We are given information that eliminates only one of the 3 outcomes for Family A (G-G). Family B can only have the first two outcomes (B-B, B-G) since it tells us that B comes first. 2 outcomes, one with a girl. You can dismiss it all you want, but it's right.

People have been studying this for years. You can see all the fun world of sitting around thinking about this here: https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

[WaitTilNextYear]

re: Off-Topic

Agree to disagree. I don't consider B-G and G-B to be independent of one another.