A graph of $x$ versus $t$ is a parabola, because $x \propto t^{2}$. But if you plot $x$ versus $t^{2}$, the resulting graph will be a straight line, with slope $\frac{1}{2} a$, as shown below. Make a graph with your values of $x_{n}$ on the vertical axis and your times squared on the horizontal. Determine the slope, and use it to find the acceleration of the car. (Attach the graph to the Laboratory Report.)
$$
\begin{array}{rlrl}
x & = & \frac{1}{2} a & t^{2} \\
\downarrow & & \downarrow & \downarrow \\
y & = & m & x
\end{array}
$$