Equations.

Question

The earth is covered by approximately 360 mill km squared of water.  If the total surface area is 510 mill km squared, what percent is water?  Rounded to the nearest tenth of a percent . 

Answer 1

calculate the ratio of water area to total surface area: 360 / 510 = 0.70588 which you convert to percentage by shifting decimal point 2 places to the right: 70.6%

 

(in the ratio, since both numbers were millions of sq km, that part can be omitted from both numerator & denominator)