At 10 p.m., 2 million people had seen the movie.
The f(3) is how many hours after it was released; If it was released at 7pm, add 3 to 7 and you'll get 10pm.
N represents how many people have watched it since it has released in millions. So, if N is 2, then 2 million people have watched it.
Hope this helps!
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