How would you do this maths question?

Mr and Mrs Jones have two children. The youngest child is called Helen. What is the probability that Mr and Mrs Jones have 2 daughters?

I have a feeling that I'm overcomplicating what is a rather simple question

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Reply 1

RDKGames

Study Forum Helper

Original post by chandmeister

A half. Eliminating the gender of one child leaves room for only 2 options for the other child. Either that, or I am missing complexity here. It's a rather simple question.

(edited 7 years ago)

Reply 2

Zacken

Original post by RDKGames

A half. Eliminating the gender of one child leaves room for only 2 options for the other child. Either that, or I am missing complexity here. It's a rather simple question.

https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

Reply 3

zainyyyyy

wouldn't you do conditional probability

Original post by Zacken

https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

Reply 4

Zacken

Original post by zainyyyyy

wouldn't you do conditional probability

Did you read the article?

Reply 5

user73867

Original post by chandmeister

Oh dear. Don't ask that question on TSR, you'll have 75 people rapidly descend on you calling you a cis gendered moron. What if Helen identifies as a donkey with 3.5 legs etc?

SS

Reply 6

Zacken

Original post by zainyyyyy

are you unable to answer a simple question or are you up your own arse for going cambridge?

lol wat

Hmmmmmm

Original post by Zacken

Did you read the article?

Original post by zainyyyyy

are you unable to answer a simple question or are you up your own arse for going cambridge?

I think someone's salty

(edited 7 years ago)

Reply 9

Kryptonian

Original post by Zacken

https://en.wikipedia.org/wiki/Boy_or_Girl_paradox

Wikipedia lies. I wouldn't trust it mate. Even I could edit it and type in some bs.

Reply 10

zainyyyyy

salty about?

him going cambridge doesnt mean he's better than me

Original post by ValerieKR

I think someone's salty

Reply 11

RDKGames

Study Forum Helper

Original post by zainyyyyy

salty about?

him going cambridge doesnt mean he's better than me

Where did you pull Cambridge from? What does that have to do with anything???

Reply 12

Zacken

Original post by Kryptonian

Wikipedia lies. I wouldn't trust it mate. Even I could edit it and type in some bs.

http://math.stackexchange.com/questions/15055/in-a-family-with-two-children-what-are-the-chances-if-one-of-the-children-is-a

Better? It's a well known paradox.

Reply 13

ValerieKR

Original post by zainyyyyy

salty about?

him going cambridge doesnt mean he's better than me

You took personal offence at a simple question - nobody was/is thinking 'haha i'm better than you' and he never even mentioned anything about Cambridge nor valuation of people based on maths abilities.

(edited 7 years ago)

50% me thinks

Original post by chandmeister

B = Boy G = Girl
BB = 0.25
BG | GB = 0.50
GG = 0.25

Reply 16

mik1a

Original post by skkrrr

B = Boy G = Girl
BB = 0.25
BG | GB = 0.50
GG = 0.25

See above- you are not incorporating useful information that tells you BB = 0

Reply 17

skkrrr

Original post by mik1a

See above- you are not incorporating useful information that tells you BB = 0

What do you mean? Nothing in the question tells you the gender of 'Helen' or there is no boys. So you have to assume Helen can be male or female meaning what I said above is correct in that sense?