2009-03-12, 06:15 PM
Alloy Wrote:Ah, but the question is not how many possibilities can be there. It's asking for the gender of a separate child from the other. If the order had any importance, yes, 1/3.
However... We have this two separate possibilities:
OUTCOME #1
Child #1 = Boy
Child #2 = Unknown
Child number 2: 50% chance to be boy - 50% chance to be girl
OUTCOME #2
Child #1 = Unknown
Child #2 = Boy
Child number 1: 50% chance to be boy - 50% chance to be girl
I can't see why it's harder to give birth to another male after giving birth to another. Because, after all, probability is about that.
The thing here is that it's not harder to give birth to a male after giving birth to another. The thing is that they have already been born. Say, you give life to two children. Then the following sequences are available:
BB
BG
GB
GG
Now, what is the chance of having 1 boy and 1 girl? that's 1/2. The chance of having 2 boys are 1/4.
Now, we already know that there is a boy in this combination. That leaves the 2 girls out.
BB
BG
GB
The 1 boy 1 girl probability is now 2/3, and 2 boys are 1/3.
Cyadd Wrote:This is kinda like if a coin gets head 5 in a row. What is the next flip going to be? Most people would say tails, but the coin doesn't know that. There is an equally chance of getting a heads again. The same here, there a equally likely chance of getting a boy or girl. Actually, the real percentages of guy to girl are 52%ish to 48%ish, respectively.
Read above.
And mang, I found the riddle:
Two Boys problem. Didn't know she was the one who "gave the answer" to this one though.