Harry is counting the hours that he sleeps. On Monday night, he sleeps for 8 hours. On Tuesday night, he sleeps for 7 hours. On Wednesday night, he sleeps for 8 hours. On Thursday night, he sleeps for 10 hours. On Friday night he sleeps for 7 hours. What is the average number of hours that Harry sleeps in one night?
Please reason step by step, and put your final answer within \boxed{}.
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