How much of the Earth's surface is covered by oceans?

• A. 71%
• B. 60%
• C. 50%
• D. 80%

Answer: (A)

The important idea here is recognizing how much of Earth’s surface is covered by water versus land. Oceans account for about 71% of the planet’s surface. You can think of it this way: Earth’s total surface area is roughly 510 million square kilometers, while the oceans cover about 361 million square kilometers. 361 divided by 510 is roughly 0.708, or about 71%.

So, the 71% option is the best fit because it matches the actual proportion of ocean to total surface. The other numbers—60% and 50% would underestimate how much of the surface is ocean, and 80% would overestimate it.