Question

Keith is saving money for a car. He has saved the same amount each year for the past three years, and records how much he has at the end of each year in the table below.
Year
\[1\] Year
\[2\] Year
\[3\]
Total amount saved
\[\$1500\]
\[\$3000\]
\[\$4500\]
What is Keith's unit rate of change of dollars with respect to time; that is, how much does Keith save in one year?
The unit rate is
dollars per year.
Graph the proportional relationship described above, with the
\[x\]-coordinate representing years, and the
\[y\]-coordinate representing amount saved in thousands of dollars.

Answer 1

From the table the amount increases by \$1500 each year (3000−1500 = 1500, 4500−3000 = 1500).

Unit rate = 1500 dollars per year.

If y is amount saved in thousands of dollars and x is years, the proportional relationship is
y = 1.5x.
Points to plot: (0,0), (1,1.5), (2,3), (3,4.5). Draw the straight line through these points (and the origin).