People pass each other on a busy city street while talking on their cellphones .
There is a better than even chance that a man bumps into a passerby while looking down at his phone .
There is a better than even chance that a man bumps into a passerby while looking down at his phone .
It is improbable that a man bumps into a passerby while looking down at his phone .
A man bumps into a passerby while looking down at his phone .