A woman with a backpack sitting outside a building with others .
Chances are about even that a woman wearing a backpack chats with her co-workers outside her office building .
Chances are about even that a woman wearing a backpack chats with her co-workers outside her office building .
It is impossible that a woman wearing a backpack chats with her co-workers outside her office building .
A woman wearing a backpack chats with her co-workers outside her office building .