Math Help - Probability measure of condition expectation

1. Probability measure of condition expectation

I kniw $Q(A) = P(AnB)/P(B)$ but nor really sure where to go with this next, could someone please provide the next step for me please.

Thanks.

2. Re: Probability measure of condition expectation

Originally Posted by Helpmeplease1
I kniw $Q(A) = P(AnB)/P(B)$ but nor really sure where to go with this next, could someone please provide the next step for me please.
Show:
1) $\left( {\forall A \in F} \right)\left[ {\mathbb{Q}(A) \leqslant 1} \right]$

2) $\mathbb{Q}(\Omega)=1$

3) If $\{G,H\}\subset F\text{ and }G\cap H=\emptyset\text{ then }\mathbb{Q}(G\cup H)}=\mathbb{Q}(G)}+\mathbb{Q}(H)}$.