PROBABILITY RULES

[SARAHI07]

I NEED HELP WITH THIS
P(B)=.2 P(A)=.7 AND P(A AND B) =.14
WHAT IS P(A|B)??

 

[soroban]

Hello, SARAHI071

$\displaystyle P(B)\,=\,0.2,\;\;P(A)\,=\,0.7,\;\;P(A\,\cap\,B)\,=\,0.14$

Find $\displaystyle \,(A|B)$

Are you familiar with Bayes' Formula?

$\displaystyle \;\;\;P(A|B)\;=\;\frac{P(A\,\cap\,B)}{P(B)}$

 

[SARAHI07]

YES I AM FAMILIAR BUT IT GOES LIKE THIS
P(B|A)=P(A AND B)
P(A)
AND I AM NOT SURE HOT TO CHANGE THAT TO

P (A|B)= P(B AND A)
P(B)
BECUASE OTHERWISE IT WILL BE

P(B|A)=.14/.2=.7
SO P(B|A)=.7[/quote]

 

[SARAHI07]

SORRY I PLUG THE NUMBER WRONG
P(B|A)=.14/.7
P(B|0)=.2
BUT I DON'T KNOW WHAT (B AND A) IS SO I'M CONFUSED PLEASE HELP ME

 

[soroban]

Hello, SARAHI07!

Don't kick yourself too hard . . .

BUT I DON'T KNOW WHAT (B AND A) IS

$\displaystyle P(A\,\cap\,B)\;=\;P(B\,\cap\,A)$

 

[SARAHI07]

DID I WORKED THE PROBLEM CORRECTLY AND HOW WOULD I KNOW IF THEY ARE INDEPENDENT OR NOT