For Exercises 7 and 8, refer to Figure A, which follows. At the beginning of this sectio...

For Exercises 7 and 8, refer to Figure A, which follows. At the beginning of this section it was mentioned that for sufficiently short periods of time, the graphs of many real-world quantities can be approximated quite accurately by a straight line. For instance, the following graph provides a close approximation to U.S. population data for the years 1970–1990.

What is the slope of the population graph in Figure A? (Be sure to include units with your answer.)