The population of the United States from 1970 to 2010 can be modeled by a function where

p(t)
is the population (in millions) and
t
is the time in decades since 1970. Some values for this function are shown in the table. (Note:
t=0

t,0,1,2,3,4

p(t) 203,227,249,281,309

What was the average rate of change, in millions of people per decade, in the U.S. population from 1970 to 2000? Round to the nearest whole number.

1 answer

To find the average rate of change from 1970 to 2000, we need to calculate the change in population from t=0 to t=3, and then divide by the time passed:

Change in population = p(3) - p(0) = 281 - 203 = 78 million

Time passed = 3 decades

Average rate of change = Change in population / Time passed
Average rate of change = 78 million / 3 decades = 26 million per decade

Rounded to the nearest whole number, the average rate of change in the U.S. population from 1970 to 2000 is 26 million people per decade.