Geography Earth's radius is approximately 4000 mil . About two-thirds of Farth's surface is covered by water. Dstimate the land area on Earth. Q

We begin by finding the total surface area of the Earth, which is a sphere with radius R ≈ 4000 miles. The surface area (A_total) of a sphere is given by   A_total = 4πR². Plugging in R = 4000 miles:   A_total = 4π(4000)² = 4π(16,000,000) = 64,000,000π square miles. Using an approximate value of π ≈ 3.14:   A_total ≈ 64,000,000 × 3.14 ≈ 201,000,000 square miles. Since about two‐thirds of Earth's surface is covered by water, the remaining one‐third is land. Therefore, the land area (A_land) is   A_land = (1/3)A_total ≈ (1/3)(201,000,000) ≈ 67,000,000 square miles. So, the estimated land area on Earth is approximately 67 million square miles.