earths radius is approximately 4000 miles. about two-thirds of earth's surface is covered by water. estimate the land area on earth

Question

Step by Step

Answer 1

To begin this problem we need to figure out what the earth's surface area is. To do this, we can use the equation for the surface area of a sphere:

SA = 4πr²

We're given the radius to be 4000 miles, so putting that in for r we get:

SA = 4π(4000)^2

SA = 2 × 10⁸ miles (otherwise known as two hundred million miles)

Now that we have Earth's total surface area we can use the fractions given in the problem to figure out how many miles of land there are. We're told that 2/3 is water, which means that 1/3 must be land to add up to 100% of the total surface. So to find what 1/3 of a value is we just multiply them together so:

SA × ⅓ = amount of land

(2 × 10⁸) × ⅓ = (2 × 10⁸) / 3

land ≈ 6.7 × 10⁷ miles

See if you can write that out as a step-by-step solution.