Question on false information

[Seb86]

What if :

1) Player A moves all in and says he has exactly 100$, player B calls and after the showdown won by player A,player A annonces that he acutally had 150$. Does player B have to pay 150 ?

2)Same situation but player A says he has about 100$ and has actually 150.

3)The dealer informs player B that player A has 100 but player A has 150.

I think that in the third case player B shouldnt pay more than 100$ as the information came from the dealer.

The second happened to me (a guy moved in and told me he had 100 when he actually had 150) and I though it was my fault as I should have ask the dealer.

Situation A I have no idea what is the rule.