Mrs Smith has two kids.
One of them is a boy.
What is the probability that the other is also a boy?
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One of them is a boy.
What is the probability that the other is also a boy?
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Mrs. Smith's kids
- Thread starter megafiddle
- Start date
Can't be answered with the information you provided. We don't know if Mrs Smith gave birth to both kids or adopted. We don't know if Mr Smith is the father of both. We don't know if Mrs Smith is the biological mother of both. We don't know if they are different ages or twins. There's too many assumptions we'd have to make.
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50%...
Am I missing something? Haploid cell fusion occurs independently per each occurrence... Right?
Am I missing something? Haploid cell fusion occurs independently per each occurrence... Right?
Don't overcomplicate it. It's as simple as it sounds. Mrs. Smith gave birth to both kids, not twins. In other words, not a trick question.
No, just one woimen with two independantly born kids. No tricks.
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I'm not overly complicating it. There's too many unknown variables. We can't even assume Mrs Smith is the control or that the other child is not a hermaphrodite. Why didn't you use coin tosses instead of children?
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What's unknown? Birthrate is 50/50 for male/female. It is slightly biased, but assume 50/50.
But, ok. Same thing with coin tosses:
You flip two coins. One of those is heads. What is the probability that the other is also heads?
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Since we don't know which coin toss was heads, it's 1 in 3 chance that both will be heads:
..........1st Toss..........2nd Toss
1)...........H.......................H
2)...........H.......................T
3)...........T.......................H
4)...........T.......................T
We know it's not the fourth possibility (TT), so that makes it a 1 in 3 chance.
But if we knew which coin toss was heads (in this example we'll say the 1st) then it's a 1 in 2 chance the second will be heads:
..........1st Toss..........2nd Toss
1)...........H.......................H
2)...........H.......................T
..........1st Toss..........2nd Toss
1)...........H.......................H
2)...........H.......................T
3)...........T.......................H
We know it's not the fourth possibility (TT), so that makes it a 1 in 3 chance.
But if we knew which coin toss was heads (in this example we'll say the 1st) then it's a 1 in 2 chance the second will be heads:
..........1st Toss..........2nd Toss
1)...........H.......................H
2)...........H.......................T
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The outcome of 1 does not change the probability of #2. SO the chance is 50%.
If you had asked the outcome of both children, then you end up with a relationship.
Actually, with the way you phrased it, it's 0 percent. You already said "one of them is a boy". You should have said, "the first is a boy, what is the probability of the second one also being a boy."
In other words, even math problems have room for grammar nazis.
In other words, even math problems have room for grammar nazis.
He didn't say "Only one of them is a boy."
If he said the first child was a boy then it's a 1 in 2 chance. There are only two possibilities:
1) Boy/Girl
2) Boy/Boy
2) Boy/Boy
But since he didn't say which child was a boy it's a 1 in 3 chance. There are three possibilities:
1) Boy/Girl
2) Boy/Boy
3) Girl/Boy
2) Boy/Boy
3) Girl/Boy
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