propsguy

Yes, we have gone over and over it, but I've been spurred to attempt to make my point again. I will agree that the answer is supposed to be 1/3;1/3 is the answer the judges are looking for. But as the puzzle is written, the answer is 1/2. The puzzle is written as: "Ok, so Teanchi and Beanchi are a married couple (dont ask me whose he and whose she)! They have two kids, one of them is a girl, what is the probability that the other kid is also a girl. Assume safely that the porbability of each gender is 1/2." The puzzle should have been written as: Ok, so Teanchi and Beanchi are a married couple (don't ask me who's he who's she)! They have two kids. At least one of the kids is a girl. What is the probability that both kids are girls? Assume safely that the probability of each gender is 1/2." There is a big diffence between the two puzzles above (aside from spelling and grammar mistakes). The way the puzzle was presented, we are asked the probability of one child. That "other kid". The probability of any "other kid" being a girl is 1/2. The way the puzzle should have been presented, the answer is 1/3. The way it should have been presented makes the gender of both children a variable. The way it was presented makes the gender of only one of the kids a variable. Not a particular kid, as I may have previously indicated, but one of them. Take yer pick! In the simplest terms, the 1/3 camp has come to their answer using the gender of both kids as variable. As a member of the 1/2 camp, I have come to my answer using the gender of only one kid as variable. Just as the question asks: "What is the probability the other kid is also a girl." I don't care which of the kids is the "one of them" girl. We are asked about the probability of "the other kid." We are never asked about the probability of both kids being girls. (By the by, I think this is a great puzzle, and a great forum. Thanks.)

"One of them is a girl" means the same exact thing as "One of which is a girl"! You're saying that adding "at least" to "One of them is a girl" changes the meaning? It doesn't! Did you think that "One of them is a girl" didn't mean at least one? Did you think it meant both? Oh really? So which one did the OP assign, the first or the second? The answer is 'neither'. "One of them" means either one of them. Not the first and not the second. Yup! Ok guys, I was willing to let it go, but now I've been forced to reach into my bag of tricks and open up a can of logical whup-a** on you all. "One of them is a girl. What is the probability the other kid is also a girl?" "One of them." "The other kid." and again, "One of them." "The other kid." I'm not saying the OP assigned one of the children to be a girl. The question itself assigns one of them. Seems clear to me: There is "one", and there is the "other." We are asked about the probability of "The other kid." I don't care if it's the first or the second born. I don't care how you look at it: "One of them is a girl." As soon as you ask about "the other" you've made that "other" the subject of the probability. And the probability of "the other one" being a girl is 1/2. Nuff said.

Ok, lets look at it this way (for clarity am stating the whole problem again..) A drawer has 5 black and 5 white socks. Your task is to pick a black pair, HOWEVER on removing a sock you are supposed to put it back if its not black. What is the probability of having a black pair in the 5th draw, 10th draw, 50th draw... Solution approach for a black pair on 2nd draw... To get a black pair on the 2nd draw, both the 1st draw and 2nd draw must be black. P(getting a black sock on 1st draw) = 1/2 P(getting a black sock on 2nd draw) = 4/9 (Since 1st sock was black it is not replaced leaving 4 black socks of total 9) So, the probability of getting a black pair on 2nd draw is 1/2 * 4/9 = 2/9. Similarly for getting a black pair on 3rd draw: 1) One of the 1st 2 picks have to be black - probability of either 1st OR 2nd resulting in black sock AND 2) 3rd draw must be black.. so y'all get the idea, try to figure a general formula.. And, since it is a probability question, the answer will have to be between 0 and 1 (both inclusive). That's about what I did to get my answer above. 1:4.5 could have read 2/9. The probablility is once in wvery 4.5 draws.

1) Your word.

By Jove, I think I've got it, though Mdsl seems to have posted a response too. Before I read his, I'll submit mine.... The chances of getting a black pair "in" any of the mentioned draws is 1:4.5

hmmmm. maybe "what is (at my) computer keyboard"

I would guess it has something to so with him starting in, say, Hawaii or Alaska, and flying at a precise speed before landing in specific locations. Maybe the earth's rotation affecting his southward bearing? Or, Maybe it is just too hard.

Holy crap is that good Writersblock! I'm looking for the "Bow-down" key on my computer.

what is (at my) computer??

I think it might be a not-so-sneaky way of saying "I read too much into the puzzle" I thought the puzzle was working with an additional, or deeper twist: like: "you have two coins in your pocket totalling 30 cents in value. One of them is not a quarter" That classic works as a puzzle, specifically because it does assign. So when I looked over the words "one of them" I took that to be a crucial part of the puzzle. I've been wrong before and I'll be wrong again Dammit. Sneaky?... not so much.

7. Your task is to pick a black pair, on removing a sock you are supposed to put it back if its not black. What is the probability of having a black pair in the 5th draw, 10th draw, 50th draw Oww, my head hurts. A question for you: If the first sock happens to be a white one, and you put it back does the next sock picked count as the 2nd draw, or the 1st? I'm assuming that you mean it to count as the 2nd. And so on....

this is the problem. let me requote the important part (middle line) "They have two kids, one of them is a girl, what is the probability that the other kid is also a girl." "they have two kids." They already have them. They're not expecting kids... they already have both of them born. The kids could be 20 and 18 years old for all we care. "One of them is a girl" okay... so if we have two kids, already born, and we can rule out B/B: G/B B/G G/G "what is the probability that the other kid is also a girl." not: "what is the probability that the other kid will be a girl." In that case it would be 1/2, since the other child does not affect the probability. But it doesnt say that. It said "is also a girl". The child is already born. it all comes down to two sides: Side A (answer is 1/2): We're looking at the second child's birth as an independent event. Side B (answer is 1/3): We're looking at both together. and I am sorry to say Side B is right (as I was on Side A for quite some time) Why? Because the second child has already been born. We dont care what was the probability that it was boy/girl while it was in its mother's womb. We know thats 1/2. The fact is, the gender has already been determined. We're just trying to figure out the probability they are both girls. Since the options are: G/B B/G G/G we can safely say, G/G has a 1/3 chance. There is no fallacy. There is no bla-bla-bla. It all comes down to wording: the "other kid" is already born. The solution doesnt call for the probability that the other kid will be a girl. It calls for the probability that they are (as in right now) BOTH girls. We're not looking at one girl's chances. In that case there would be two options: B G but we're not. BECAUSE OF THE WORDING, we are looking at both children at once: G/B B/G G/G It is 1/3. It pains me to say this (I defended 1/2 for a while until i realized i was wrong) but I'm not being bitter and I'm trying to prove what I now see is right. its a fine line, based on skale's wording. but the answer is 1/3. I rest my case. I think this topic should be done. The discussion cant go much elsewhere. Thanks Unreality. And Martini. I've read your explanation and the rest of the thread. And I know how the answer is supposed to be 1/3 But... It does come down to the wording. "One of them is a girl" versus "One of which is a girl" The statement in the riddle is not "One of which" though. Nor is it "At least one of them is a girl" It's a matter of assigning. As soon as you say "one of them" you've assigned, say, the first born, or the second born to be a girl. If one of them, say the first born, is in fact a girl, the chances of the other being a girl are 50%. in: G/B B/G G/G it does look to be 1/3. But, by assigning, by saying "one of them is a girl" I submit that you can, in a way, add a second G/G set. Or, of those 6 kids, 4 are girls. The chances of "one of them" girls having a sister is 50%. Semantics maybe, but that's how I see the puzzle. But then again, I may just be "one of them" guys.

Like a mom's trick with two children and the last piece of cake: one gets to cut, the other gets to choose.

Hamilton was Burr's second in the duel. They were on the same 'side'?

An umbrella?