In 1900 ,a certain country's population was 70,512,134and its area was 2,891,242 square miles. In 1980 ,the country's population 285,292,624 and its area was 3,534,621 square miles.
a. Find the population density of the country, to the nearest tenth, in 1900 and in 1980.
b. Find the percent increase in population density, to the nearest tenth of a percent, from 1900 to 1980.