Hypothesis
Let there is no air drag or any other resistance force due to surrounding
Now the force equation of ball is given as
[tex]F = mg[/tex]
[tex]ma = mg[/tex]
[tex]a = g[/tex]
so the ball will be dropped down by acceleration a = g and this acceleration is independent of size and mass of the ball
So in this case both balls will be dropped by same acceleration.
So here both balls will hit the ground at same time