The size of the U.S. civilian workforce for the years from 1950 and projected to 2050 can be approximated by a linear equation determined by the line connecting the points (1950, 62.2) and (2050, 191.8), where the x-coordinate is the year and the y-coordinate is the number in the civilian workforce (in millions) in year x.

(a) Write the equation of the line connecting the two points.

(b) Interpret the slope of this line as a rate of change?