Which is likely to be more common in our galaxy: white dwarfs or black holes? why?

In an experiment, a die is rolled continually until a 6 appears, at which point the experiment stops. what is the sample space of this experiment. let en denote the even that n rolls are necessary to complete the experiment. what points of the sample space are contained in en? describe the event (∪ ∞ n=1en) c .