How to solve independent events problems (probability): example and its solution.
In the first selection,
the probability of selecting a gray card is 8/15.
In the second selection,
the probability of selecting a gray card is also 8/15.
The probability didn't change
because of the replacement.
So the first selection
didn't affect the second selection.
Just like this case,
if the first event didn't affect the next event,
then those two events are called independent events.
So the probability is (8/15)⋅(8/15).