Saturday, April 14, 2012

Area Covered by World Population

Have you ever wondered what percentage of the earth's land surface would be covered by the world's population?  If you want to do this, you need 3 things:
  1. a value P for the total number of people of the world's population
  2. a value A for an area that the average person covers
  3. a value S for the area of the earth's land surface
You also need a formula to calculate the percentage, and it is 100 multiplied by P multiplied by A divided by S percent.

Let's say that the population P is 7 billion, the area that the average person covers A is 2 square feet, and the area of the earth's land surface S is about 1.6 times 10 to the power 15 square feet.  Now we are ready to come up with a percentage:
  • 100 x ( P x A / S ) % = 100 x 7 x (10^9) x 2 / (1.6 x 10^15) % = 0.000875 %
That is a miniscule amount of area compared to the total area of the earth's land surface.  To get an idea of how much area this is, we just need to multiply this percent by the total area of the earth's land surface:
  • 1.6 x 10^15 x 0.000875 x 0.01 square feet = 14 billion square feet
A square mile is about 28 million square feet, so 14 billion square feet is about 500 square miles.  The state of Rhode Island is more than twice that amount.  This means that we can double the world's population and it will still fit into Rhode Island.

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