The population in the united states in 2000 was about 281 million people. in 2015, it was 321 million people. from 2000 to 2015, the population increased %.
Given:
Year 2000 = 281 million people
Year 2015 = 321 million people
321 M - 281 M = 40 M
An increase of 40 million people.
40M/281M = 0.14 or 14%.
From 2000 to 2015, the population increased by 14%