Compare the population per square mile in Asia to the population per square mile in North America for the year 2000. Population in Asia in 2000 was 4,028,000,000. Population in North America in 2000 was 305,000,000.

look up the area of asia and north america, then divide the population of each by that area.

BTW, the population of North America in 2000 was:
USA - 280 000 000
Canada - 30 000 000
Mexico - 100 000 000
so you are off by a signigicant 100 000 000, or a 33% error!