Question

Please help! need help figuring this question out

Answer 1

The earth is a spherical object, and you're correct, its radius is 3959 miles.

we know 71% of that is covered in water, that means 29% of that is not, 71%+29% = 100%.

well, let's recall that whatever% of anything is just (whatever/100) * anything.

now, how many square miles is its surface anyway?

$\bf \textit{surface area of a sphere}\\\\ SA=4\pi r^2~~ \begin{cases} r=radius\\ -----\\ r=3959 \end{cases}\implies SA=4\pi (3959)^2 \\\\\\ SA=62694724\pi$

since 71% is already covered with water, we only need the other 29% covered, what is 29% of 62694724π, well, is just (29/100) * 62694724π.