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Wait. What? The author says there can only be one BB but that there can be both GB and BG? What he's doing here is saying that birth order functionally doesn'

by bpm140 15y ago

Wait. What? The author says there can only be one BB but that there can be both GB and BG? What he's doing here is saying that birth order functionally doesn't matter if the sibling is a boy, but it does matter if it's a girl. How is this correct? If you keep comparing apples to apple you get: Older Boy / Boy Boy / Younger Boy Older Girl / Boy Boy / Younger Girl And we're back to a 50% chance that the other child is a boy.

NickPollard 15y ago
Altogether now! Here's the chart: B G B BB BG G GB GG Satisfied?
suivix 15y ago
Since he has two children, you know first off that these are all equal chance historically: BB BG GB GG Now since you know the child is a boy, it eliminates the fourth option. So now we have these possibilities: BB BG GB In only one of these is the other child a boy, so the chance is 1/3.
- bpm140 15y ago
  This explanation makes a ton of sense. I get it now. Thank you.
  - suivix 15y ago
    Also I don't think the exact day of birth being Tuesday makes one bit of difference to the gender. For example, if you were to say the known boy was born crying, and the chance of this is 70%, it doesn't affect the gender of the other children. It's just useless trivia.
    - jules 15y ago
      That's not true. It does affect the probability of the other child being a boy just like being born on Tuesday does.
onemoreact 15y ago
The Monty hall problem is based on the idea that you will always do the same thing in response to my choice aka he can always pick an open door. It's feels add to think about it in terms of what's already happens but seems more reasonable to say it in terms of something that will happen. So if you say I will flip 2 coins and if I get zero heads I will flip again. So, if the first coin is a head second one either a head or a tail, but if it's a tail you know the second one is a head or I would have flipped again. Thus 3 options one of which is HH. Assuming you used the same approach with the Tuesday boy problem, aka the first one can be BMTWTFSS or GMTWTFSS and the second one can be BMTWTFSS, GMTWTFSS but if I don't get a BT from the first or second try's I will pick again. Thus BT + BMTWTFSS or GMTWTFSS, OR BMTWTFSS or GMTWTFSS + BT minus a BT,BT which would otherwise be counted twice. Thus it's 14 + 13 options with 7 + 6 being BB. Which works out to 13/27.

by bpm140 15y ago

NickPollard 15y ago

Altogether now! Here's the chart: B G B BB BG G GB GG Satisfied?

suivix 15y ago

Since he has two children, you know first off that these are all equal chance historically: BB BG GB GG Now since you know the child is a boy, it eliminates the fourth option. So now we have these possibilities: BB BG GB In only one of these is the other child a boy, so the chance is 1/3.

bpm140 15y ago
This explanation makes a ton of sense. I get it now. Thank you.
- suivix 15y ago
  Also I don't think the exact day of birth being Tuesday makes one bit of difference to the gender. For example, if you were to say the known boy was born crying, and the chance of this is 70%, it doesn't affect the gender of the other children. It's just useless trivia.
  - jules 15y ago
    That's not true. It does affect the probability of the other child being a boy just like being born on Tuesday does.

onemoreact 15y ago

The Monty hall problem is based on the idea that you will always do the same thing in response to my choice aka he can always pick an open door. It's feels add to think about it in terms of what's already happens but seems more reasonable to say it in terms of something that will happen. So if you say I will flip 2 coins and if I get zero heads I will flip again. So, if the first coin is a head second one either a head or a tail, but if it's a tail you know the second one is a head or I would have flipped again. Thus 3 options one of which is HH. Assuming you used the same approach with the Tuesday boy problem, aka the first one can be BMTWTFSS or GMTWTFSS and the second one can be BMTWTFSS, GMTWTFSS but if I don't get a BT from the first or second try's I will pick again. Thus BT + BMTWTFSS or GMTWTFSS, OR BMTWTFSS or GMTWTFSS + BT minus a BT,BT which would otherwise be counted twice. Thus it's 14 + 13 options with 7 + 6 being BB. Which works out to 13/27.