To determine which distance uses the most appropriate units, let's convert all the distances to kilometers to make a comparison easier:
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3 × 10^2 kilometers: This is already in kilometers.
- Value: 300 kilometers
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3 × 10^5 meters: To convert meters to kilometers, we divide by 1,000 (since 1 kilometer = 1,000 meters).
- Value: \( \frac{3 \times 10^5}{1,000} = 3 \times 10^2 \) kilometers = 300 kilometers
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3 × 10^7 centimeters: To convert centimeters to kilometers, we divide by 100,000 (since 1 kilometer = 100,000 centimeters).
- Value: \( \frac{3 \times 10^7}{100,000} = 3 \times 10^2 \) kilometers = 300 kilometers
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3 × 10^8 millimeters: To convert millimeters to kilometers, we divide by 1,000,000 (since 1 kilometer = 1,000,000 millimeters).
- Value: \( \frac{3 \times 10^8}{1,000,000} = 3 \times 10^2 \) kilometers = 300 kilometers
All the given distances equal 300 kilometers when converted. However, when selecting the most appropriate unit for a road trip, kilometers are typically the most suitable distance units for a long travel distance compared to meters, centimeters, or millimeters.
Considering this, 3 × 10^2 kilometers is the most appropriate unit.