Premise: Several people walk up a staircase .
Correct statement: Chances are about even that the people are coworkers .
Incorrect statement: It is certain that the people are coworkers .
Correct statement: It is certain that people are going up .
Incorrect statement: Chances are about even that people are going up .
Correct statement: It is probably the case that the people are chatting as they walk .
Incorrect statement: It is impossible that the people are chatting as they walk .
Correct statement: There is almost no chance that several people race up a flight of stairs .
Incorrect statement: It is highly likely that several people race up a flight of stairs .
Correct statement: It is impossible that people exercise together
Incorrect statement: It is certain that people exercise together