A Researcher Wanted to Determine If Using an Octane Booster

A researcher wanted to determine if using an octane booster would increase gasoline mileage. A random
sample of seven cars was selected; the cars were driven for two weeks without the booster and two weeks
with the booster.
$$\begin{array} { | l | l | } \hline \text { Miles / Gal Without } & \text { Miles / Gal With } \\\hline 21.2 & 23.8 \\\hline 25.4 & 25.6 \\\hline 20.9 & 22.4 \\\hline 27.6 & 28.3 \\\hline 22.8 & 24.5 \\\hline 27.3 & 28.8 \\\hline 23.4 & 25.2 \\\hline\end{array}$$
-A running coach wanted to see whether runners ran faster after eating spaghetti the night before a race. Twenty-four random runners were chosen for this study. They ran a 5-kilometre race after having a
Normal dinner the night before, and then a week later, re-ran the same race after having a spaghetti dinner
The night before. Their results (in seconds) are in the table below. At ${ } ^ { \ddagger } = .01$ , what is the test value for
This test? $$\begin{array} { | l | c | c | c | } \hline & \text { Regular Dinner } & \begin{array} { c } \text { Spaghetti } \\\text { Dinner }\end{array} & \begin{array} { c } \text { Difference } \\\text { by Runner }\end{array} \\\hline \text { Sample mean } & 1000 & 980 & - 20 \\\hline \text { Sample variance } & 3000 & 2800 & 400 \\\hline\end{array}$$

A) -3.41
B) -1.00
C) -0.26
D) -4.90