The human population of the earth is approximately 8 billion and is increasing at approximately 2% per year. The diameter of the earth is approximately 8000 miles, and the surface of the earth is approximately two-thirds water. (a) Calculate the population doubling time, then set up a spreadsheet that will show i. ii. iii. the population the number of square feet of land area per person the length of the side of a square that will produce the required area per person. Carry out the spreadsheet for 20 doubling times if the rate of population increase remains constant. (b) What conclusions can you draw from this exercise?