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Question

The population of the United States was about 280 million in 2000 and about 310 million in 2012. What was the annual rate of change in population from 2000 to 2010?

Answer 1

rate = change in population divided by the time interval

change in population = (310 - 280) million = 30 million

time interval = (2012 - 2000) years = 12 years

rate = (30 million) / (12 years) = 2.5 million/year

Assume the rate of change is constant, since no other information is given.