Question

1. about 70% of earths surface is covered by water. if the diameter of earth is about 12,750 km, find the area not covered by water to the nearest 100,000 \text{ km}^2.

Explanation:

Calculate the radius of Earth

The diameter of Earth is given as \(d = 12,750\text{ km}\).
The radius \(r\) is:

$$r = \frac{d}{2} = \frac{12,750}{2} = 6,375\text{ km}$$

Find total surface area

Using the Sphere Surface Area knowledge point:

$$A = 4\pi r^2$$

$$A = 4\pi (6,375)^2 = 162,562,500\pi\text{ km}^2$$

$$A \approx 510,705,110\text{ km}^2$$

Determine land area percentage

Since about \(70\%\) of Earth's surface is covered by water, the percentage not covered by water (land area) is:

$$100\% - 70\% = 30\%$$

Calculate the land area

Multiply the total surface area by \(30\%\):

$$A_{\text{land}} = 0.30 \times 510,705,110 \approx 153,211,533\text{ km}^2$$

Round to nearest 100,000

Rounding \(153,211,533\) to the nearest \(100,000\text{ km}^2\):

$$A_{\text{land}} \approx 153,200,000\text{ km}^2$$

Answer:

\(153,200,000\text{ km}^2\)