Premise: People walk down a flight of stone steps in public .
Correct statement: It is impossible that people walk down steps at the courthouse .
Incorrect statement: Chances are about even that people walk down steps at the courthouse .
Correct statement: It is impossible that people are exiting a library .
Incorrect statement: It is probably the case that people are exiting a library .
Correct statement: There is a better than even chance that people from a tour group walk down a flight of public steps that are made of stone .
Incorrect statement: It is highly unlikely that people from a tour group walk down a flight of public steps that are made of stone .
Correct statement: There is a better than even chance that two people are walking home together .
Incorrect statement: There is almost no chance that two people are walking home together .
Correct statement: It is impossible that people head down into the metro station .
Incorrect statement: It is probable that people head down into the metro station .