I have 2 kids. At least 1 of them is a boy What's the probability that both are boys?

[kanis999]

So many people failing at statistics...

The probability is 50%. The first child does not affect the second child's gender probability and there are two possibilities (boy + boy and boy + girl) with equal probabilities, so 50%.

Most succinct way of saying what should have been obvious. Grats.

[Pandai]

Isn't there a possibility* of the baby being born a hermaphrodite?

[SonOfAristaeus]

When you have 2 kids, there are 4 possibilities for the gender distributions. With B represents Boy and G representing Girl, there's:
GG
GB
BG
BB

We know that GG is not the case, since there's at least 1 boy. That means GB, BG, and BB remain. Here, BB is the only case that satisfies having 2 boys. Thus, the probability of having BB is 1/3rd.

GB and BG would be the same thing in the end brah + as said above the first child would be a boy, so 50% chance for the second child.

[hardbrah69]

don't see option for 100% for those of us alphas with the power to command our sperm

obviously the answer is 50% you potatoes - one event occurs of which the probability is 0.5

[pondus_levo]

about 75%

100% + 50% / 2

If we didn't know the sex of either, it would be 33%.

There is do difference between BG, and GB, the order does not matter.

[Curlzbrah]

The question sucks. The statement "One is a boy" doesn't necessarily determine from what moment we are calculating the probability.

Before knowing that one kid is a boy: 0.5^2 = 1/4

After one kid (=boy) was born, there is only one variable left: 1/2

EDIT:

GB and BG would be the same thing in the end brah + as said above the first child would be a boy, so 50% chance for the second child.

Wrong. If you ONLY do know that one is a boy, but you do not know that the first child is a boy, the chance indeed is 1/3

[DatMurse]

When you have 2 kids, there are 4 possibilities for the gender distributions. With B represents Boy and G representing Girl, there's:
GG
GB
BG
BB

We know that GG is not the case, since there's at least 1 boy. That means GB, BG, and BB remain. Here, BB is the only case that satisfies having 2 boys. Thus, the probability of having BB is 1/3rd.

I hate the misc sometimes
its 50/50
http://jfmueller.faculty.noctrl.edu/...%20teasers.pdf

[Liet]

When you have 2 kids, there are 4 possibilities for the gender distributions. With B represents Boy and G representing Girl, there's:
GG
GB
BG
BB

We know that GG is not the case, since there's at least 1 boy. That means GB, BG, and BB remain. Here, BB is the only case that satisfies having 2 boys. Thus, the probability of having BB is 1/3rd.

This is correct.

[Ranniks]

If the chance of a boy is 50% and 50% for a girl, then the chance for both is 25%. If you flip a coin twice, the chance of two times heads is: 0.5*0.5=0.25 thus 25%.

People are like:

BB
GG
BG
GB

Think of it the other way:

HH
CC
HC
CH

Flip twice, what is the chance: 0.5*0.5=0.25 = 25%.

Yeah, just like that.

[HotCheetos]

Lol at poverty math = 50%

Try again (math bachelors fyi)

[Anesthetize18]

dumbasses overthinking it (overcompensating?), intelligent miscers getting it within 2 seconds.

[zergfest]

GG
GB
BG
BB

(1 is guaranteed to be a boy). It didn't say whether it's first or 2nd.

So only remaining cases are :

GB
BG
BB

(with 1/3 chance of each one happening... since it's 1 out of 3 choices for those who are too retard for fractions)


We want BB (since that's what OP asked us to look for)

That's only 1 of the 3 options.

So it's 1/3

Lol at poverty math = 50%

Try again (math bachelors fyi)

Go back to school you retard

If the chance of a boy is 50% and 50% for a girl, then the chance for both is 25%. If you flip a coin twice, the chance of two times heads is: 0.5*0.5=0.25 thus 25%.

People are like:

BB
GG
BG
GB

Think of it the other way:

HH
CC
HC
CH

Flip twice, what is the chance: 0.5*0.5=0.25 = 25%.

Yeah, just like that.

Except he said 1 is GUARANTEED to be a boy.

so GG is not an option. Potato.

[Manne1]

wow miscers r retarded


when u have a child its either a boy or a girl so 50/50

[PRIMETIMEENT]

When you have 2 kids, there are 4 possibilities for the gender distributions. With B represents Boy and G representing Girl, there's:
GG
GB
BG
BB

We know that GG is not the case, since there's at least 1 boy. That means GB, BG, and BB remain. Here, BB is the only case that satisfies having 2 boys. Thus, the probability of having BB is 1/3rd.

is wrong because it determines the probability of 2 boys, not the
probability that both are boys given one is. Thus, this answer leaves out some
important information-- the fact that you know one child is a boy. This information
destroys the "equally likely" assumption. You can easily see that the 4 possible
outcomes are no longer equally likely when you realize that the information that one
child is a boy makes the probability of the event GG = zero.

Since births of children are independent of each other, the first child's sex has
no bearing on the other's. Since about half of the births are male, the
probability of the second child being a boy is .50.

If B1 = first child is a boy, B2 that the second is a boy, then, by the
independence rule and the formula for conditional probabilities, p(B2 | B1) =
p(B2) = .50.

[cjpinz]

its 50-50. it either happens or it doesnt.

[amikaelmorris]

The question sucks. The statement "One is a boy" doesn't necessarily determine from what moment we are calculating the probability.

Before knowing that one kid is a boy: 0.5^2 = 1/4

After one kid (=boy) was born, there is only one variable left: 1/2

EDIT:



Wrong. If you ONLY do know that one is a boy, but you do not know that the first child is a boy, the chance indeed 75%

i checked 25% originally thinking in my head but this makes more sense to me cause the births are separate events so you can't calculate probability the same way as if they happened at the same time.. either birth is 50-50 so the one being a boy leaves you with another 50-50 chance. 50% that one is a boy, 50% that both are

[Curlzbrah]

I hate the misc sometimes

He isn't wrong (srs).

If you do ONLY know that one of the kids is a boy, but you DO NOT KNOW that the FIRST kid is a boy, then the chance is 1/3. But this case is not the standard case, because usually one baby is born after the other, so you'll know most definitely what gender the first kid has.



But we could engineer a case, where the probability would be 1/3: A woman gives birth to twins, but they are taken to humidcribs. The women falls unconcious during the procedure, and when she is awake the nurse only tells her that one kid is a boy. Now the probability would be 1/3 for the second kid to be a boy.

[pondus_levo]

wow miscers r retarded


when u have a child its either a boy or a girl so 50/50

Both kids already exist. He didn't ask what are the odds of the the second child only, in which case it would be 50%. You have to factor in the existing boy, which is a known. The order does not matter.

[Curlzbrah]

i checked 25% originally thinking in my head but this makes more sense to me cause the births are separate events so you can't calculate probability the same way as if they happened at the same time.. either birth is 50-50 so the one being a boy leaves you with another 50-50 chance. 50% that one is a boy, 50% that both are

yeah I'm sorry about the 75%, got it wrong. should be p=(1/2) and p=(1/3), depending on what information the chitty problem-statement provides.

[HotCheetos]

GG
GB
BG
BB

(1 is guaranteed to be a boy). It didn't say whether it's first or 2nd.

So only remaining cases are :

GB
BG
BB

(with 1/3 chance of each one happening... since it's 1 out of 3 choices for those who are too retard for fractions)


We want BB (since that's what OP asked us to look for)

That's only 1 of the 3 options.

So it's 1/3




Go back to school you retard




Except he said 1 is GUARANTEED to be a boy.

so GG is not an option. Potato.

Guess I wasn't clear

I am laughing at peoples poverty math giving them 50%

[Liet]

lol so many unaware brahs. Answer is 1/3

[Manne1]

GG
GB
BG
BB

(1 is guaranteed to be a boy). It didn't say whether it's first or 2nd.

So only remaining cases are :

GB
BG
BB

(with 1/3 chance of each one happening... since it's 1 out of 3 choices for those who are too retard for fractions)


We want BB (since that's what OP asked us to look for)

That's only 1 of the 3 options.

So it's 1/3




Go back to school you retard




Except he said 1 is GUARANTEED to be a boy.

so GG is not an option. Potato.

are u dumb?????????????

Only possibilities are

BB

BG

If one of them is already a boy that means the second is either a boy or a girl u have a 50/50

[Psychotropic]

The answer is 1/3

No need to show the reasoning because it’s so obvious. Other posts show it

To those saying 1/2, ask yourself this problem:

I have 2 kids. What is the probability that both are boys? Using your retarded reasoning you would answer 1/3 but that is wrong.

[amikaelmorris]

bottom line: FUK MATH

[Erevan]

With genetic testing and abortion = 100%

[IPoopStandingUp]

Still 50%

u wanna test this?

[kanis999]

Guys if you know PRIOR to the 'coin flip' that one of the flips will be heads, it is essentially taking that flip out of the equation. It doesn't count any more. There is one remaining coin flip.

I'm starting to see how both sides could actually be right.

[Apocc]

The answer is 1/3

No need to show the reasoning because it’s so obvious. Other posts show it

To those saying 1/2, ask yourself this problem:

I have 2 kids. What is the probability that both are boys? Using your retarded reasoning you would answer 1/3 but that is wrong.

Actually yeah, you're right.

I retract my earlier statement about P(A I B).

It really does come down to

BB

BG

GB

and GG being eliminated since it doesn't meet the minimum 1 boy rule. So then you have 1/3 as the answer.

[amikaelmorris]

yeah I'm sorry about the 75%, got it wrong. should be p=(1/2) and p=(1/3), depending on what information the chitty problem-statement provides.

yeah actually you're right, i was working under the assumption that the boy was already in existence which isn't necessarily true given how it's worded

in that case your options are: BG, BB 1/2
if it doesn't already exist: GB, BG, BB 1/3

interesting

[povertytime]

My prayers are with you OP. Let's hope the other is a boy too.

lol'd