Question

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Water covers 708%, or about 3.61 x 10⁸ km², of the Earth's surface. Approximate the total surface area of the Earth. (Round your answer to the nearest million.)

____________ km²

Answer 1

510,000,000 million km²

Let us represent the total surface area of the earth as = x

We are told in the question that:

Water covers 70.8%, or about 3.61 × 10⁸ km², of the Earth's surface.

70.8% = 0.708

Hence,

0.708 × x = 3.61 × 10⁸

x = 3.61 × 10⁸/0.708

x = 361000000/0.708

x = 509,887,005.65km²

Therefore, the total surface are the earth approximately to the nearest million = 510,000,000 million km²

Answer 2

Answer: 510,000,000

This is the number "510 million"

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Work Shown:

The times 10⁸ means "times 100 million"

3.61 x 10⁸ = 3.61 * 100 million = 361 million

S = surface area of the earth

70.8% of S = water coverage area

70.8% of S = 361 million square km

0.708S = 361 million square km

S = (361/0.708) million square km

S = 509.887 million square km

S = 510 million square km

S = 510,000,000 square km