Final answer:
To calculate the percentage of the Earth's surface area that is land, subtract the area covered by water from the total surface area, divide by the total, and multiply by 100. Approximately 29.0% of the Earth's surface is land.
Step-by-step explanation:
If approximately 139 million square miles of the Earth's surface area is water, and we know that water covers 71% of the Earth's surface, then we can calculate the percentage of the Earth's surface that is land. To find the total surface area of the Earth, we can take the amount of surface area that is water and divide it by 0.71 (since 71% is equivalent to 0.71 when used in a calculation).
Total Surface Area of Earth = 139 million square miles / 0.71 = approximately 195.8 million square miles.
Next, we calculate the surface area that is land by subtracting the area covered by water from the total surface area.
Land Surface Area = Total Surface Area - Water Surface Area
Land Surface Area = 195.8 million square miles - 139 million square miles = 56.8 million square miles.
To find what percentage of the surface area is land, we divide the land surface area by the total surface area and then multiply by 100.
Percentage of Surface Area that is Land = (Land Surface Area / Total Surface Area) × 100
Percentage of Surface Area that is Land = (56.8 million square miles / 195.8 million square miles) × 100 ≈ 29.0%
Therefore, approximately 29.0% of the Earth's surface area is land, rounding to the nearest tenth of a percent.