a boy in a purple shirt is doing a skateboard stunt on a wooden ramp beside a white building .
Chances are about even that a boy is trying to perfect a skateboard trick his brother showed him .
Chances are about even that a boy is trying to perfect a skateboard trick his brother showed him .
It is highly unlikely that a boy is trying to perfect a skateboard trick his brother showed him .
A boy is trying to perfect a skateboard trick his brother showed him .