# Help needed for Probability qustion please

Hi,
I am struggling on a question and any help given would be much appreciated. Here it is:
A class consists of seven boys and nine girls two different members of the class are chosen at random. A is the event that {the first person is a girl} and B is the event that {the second person is a girl}. Find the probability of of B given A' (B/A')
Thanks Jack
Jack
Hi,
I am struggling on a question and any help given would be much appreciated. Here it is:
A class consists of seven boys and nine girls two different members of the class are chosen at random. A is the event that {the first person is a girl} and B is the event that {the second person is a girl}. Find the probability of of B given A' (B/A')
Thanks Jack

A' is the complement of A--i.e. A' is the event that the first person is a boy, so that P(A')=7/16.
P(B|A')=P(B n A')/P(A')=P(B and A')/P(A')=P(second person girl AND first person boy)/P(A')=(7/16).(9/15)/(7/16)=9/15
Much appreciated but unfortunately the answer according to a textbook i have is 3/5. Altough it is encouraging that both you and i both achieved the exact same result. Good try but try again - lol,
Thanks Jack
Jack
Much appreciated but unfortunately the answer according to a textbook i have is 3/5. Altough it is encouraging that both you and i both achieved the exact same result. Good try but try again - lol,
Thanks Jack

The textbook is wrong.
Hello people, are you awake?!

9/15 = 3/5!!
9/15 = 3/5
Or am I missing something?

EDIT: Beaten O: .
Ha! The prodigal mathematician.
Excuse me? Is this supposed to be a sarcastic comment aimed at me/speleo? If it is, then may I remind you that YOU are the one who was unable to see that 9/15=3/5
~Bex~
Excuse me? Is this supposed to be a sarcastic comment aimed at me/speleo? If it is, then may I remind you that YOU are the one who was unable to see that 9/15=3/5

The prodigal mathematician was intended to be self-deprecating.
prodigal $\neq$ prodigious
Jonny W
prodigal $\neq$ prodigious

I know. Prodigal=reckless.
~Bex~
Excuse me? Is this supposed to be a sarcastic comment aimed at me/speleo? If it is, then may I remind you that YOU are the one who was unable to see that 9/15=3/5

lol