Nadia is learning to play the piano. She normally makes 3 mistakes per 40 notes and can play about 60 notes a minute.  If she plays for 8 minutes how many mistakes will she make on average? Let's think first. Chain of thought:
She plays 480 notes because 8 x 60 = 480. This is 12 blocks of 40 notes because 480 / 40 = 12. She makes 36 mistakes because 12 x 3 = 36.
Therefore, the answer is 36.