Question

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Water covers 70.7%, or about 3.61 x 10⁸ km², of the Earth's surface. Approximate the total surface area of the Earth. (Round your answers to the nearest million.)

_____________ km²

Answer 1

511 million km²

Step-by-Step Explanation:

Let the total surface area of the Earth be x.

Water covers 70.7% of the total surface area of the Earth, i.e.,

70.7% of x = 3.61 x 10⁸ km²

or, 70.7x /100 = 3.61 x 10⁸ km²

or, 707x/1000 = 3.61 x 10⁸ km²

or, 707x = 3.61 x 10⁸ x 1000km²

or, 707x = 3.61 × 10^11 km²

or, x = 0.0051 × 10^11 km²

or, x = 5.1 × 10⁸ km² = 511 million km²

Hope it helps.

If you have any query, feel free to ask .

Answer 2

511 million km²

Explanation:

Let x be the approximate total surface area of the Earth.

Given water covers 70.7%, or about 3.61 × 10⁸ km², set up an equivalent ratio of percent (in decimal form) to area:

`\implies 0.707:3.61 * 10^8=1:x`

Solve for x:

`\implies(0.707)/(3.61 * 10^8)=(1)/(x)`

`\implies0.707x=3.61 * 10^8`

`\implies x=(3.61 * 10^8)/(0.707)`

`\implies x=(3.61 )/(0.707)* 10^8`

`\implies x=5.10608203...* 10^8`

One million has 6 zeros and can be written in scientific notation as:

• 1 × 10⁶

Therefore, to write x in millions as x × 10⁶, subtract 2 from the exponent and move the decimal point to the right by 2 places:

`\implies x=510.608203...* 10^6`

Therefore, the approximate surface area of the Earth is 510.608203... million km², which is 511 million km² to the nearest million.