Question

according to the general equation for conditional probablility if P(A upside down u B) = 5/9 and P(B)= 1/3 , what is P(A vertical line B)?

Answer 1

By definition of conditional probability,

$\mathbb P(A\mid B)=\dfrac{\mathbb P(A\cap B)}{\mathbb P(B)}$

Note that probabilities must always fall between 0 and 1, so $\mathbb P(A\cap B)\le\mathbb P(B)$. But we have


$\mathbb P(A\mid B)=\dfrac{\frac59}{\frac13}=\dfrac53$

and this probability is greater than 1. So the question doesn't really make sense...