Let the number of people enrolled in Medicare be represented by y
Let the year be represented by x
So that,
[tex]\begin{gathered} (x_1,y_1)=(2015,55.5\text{ million)} \\ (x_2,y_2)=(2009,46.6\text{ million)} \end{gathered}[/tex]The unit rate of change (slope) in millions per year can be calculated by:
[tex]\begin{gathered} slope=\frac{y_2-y_1}{x_2-x_1} \\ \text{Hence,} \\ slope=\frac{46.6million_{}-55.5million_{}}{2009_{}-2015_{}} \\ slope=\frac{-8.9}{-6} \\ slope=1.48 \\ \end{gathered}[/tex]Therefore, the unit rate of change in millions per year is 1.48 [Option B]
