>>> A building has 10 floors. At the ground floor, 7 people enter the elevator. At the second floor, 3 people get off and 2 people enter. At the fourth floor, 5 people get off and 2 people enter. At the seventh floor, 1 person gets off and 3 people enter. Finally, at the tenth floor, everyone remaining in the elevator gets off. The question is, How many people were in the elevator when it started its journey, and how many total people exited the elevator by the end of its journey?

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Let's analyze the sequence of events:

1. The elevator starts with 7 people.
2. At the second floor, 3 people get off, and 2 people enter, making it 7 - 3 + 2 = 6 people.
3. At the fourth floor, 5 people get off, and 2 people enter, making it 6 - 5 + 2 = 4 people.
4. At the seventh floor, 1 person gets off, and 3 people enter, making it 4 - 1 + 3 = 8 people.
5. At the tenth floor, the last 8 people get off.

Thus, the elevator started with 7 people and had 21 people get on and off during its journey, ending with 8 people at the tenth floor. Therefore, the final answer is that 8 people were in the elevator when it reached the tenth floor, and a total of 21 people exited the elevator by the end of its journey.