In science class, you learn that there are approximately 4.158 x 10^7 km^3—or 4.158 x 10^(19) L—of fresh water on Earth. You also learn that there are approximately 6.7 billion people living on Earth. According to a classmate, this works out to approximately 6.21 x 10^9 L of fresh water for each person on Earth.
Your classmate concludes that reports of water shortages in various parts of the world must be exaggerated.
Why is this an invalid conclusion? Support your answer by identifying at least two errors in your classmate's reasoning. Include any calculations that you used to arrive at your answer.