Question

It took 1649 years for the world population to double, going from .25 billion people to .50 billion people. How long did it take for the population too double once again

Answer 1

I found the missing part of this question.

Statisics on Human Population

Year A.D.            Number of People (in billions)
1650                         .50
1750                         .70
1850                         1.0
1925                         2.0
1956                         2.5
1966                         3.3
1970                         3.6
1974                         3.9
1976                         4.0
1980                         4.4
1991                         5.5
2000                         6.0
2004                         6.4

The answer is it took 200 years more to double the population from 0.50 billion to 1.0 billion people. The year was 1850.

It was in 1925 when the population double again from 1.0 billion to 2.0 billion.