A person wearing a hat and carrying a knapsack walks uphill on a sand dune under a dark , cloudy sky and leaves the only visible footprints behind .
Chances are about even that a man in a hat who has a knapsack walks quickly up a sand dune to try to get home before the cloudy skies start to rain .
Chances are about even that a man in a hat who has a knapsack walks quickly up a sand dune to try to get home before the cloudy skies start to rain .
There is almost no chance that a man in a hat who has a knapsack walks quickly up a sand dune to try to get home before the cloudy skies start to rain .
A man in a hat who has a knapsack walks quickly up a sand dune to try to get home before the cloudy skies start to rain .