Answer
There is sufficient evidence to support the claim that caffeine enhances performance.
Work Step by Step
Here we have α = 0.05 and n = 10. df = 10 - 1 = 9
Using the classical approach, we have:
$t = \frac{\bar d - µ_{d}}{s_{d}/\sqrt n}$
$ = \frac{18 - 0}{19/\sqrt 10} = \frac{18}{1.355} = 2.996$
Using Student's t distribution table, we have:
t = 1.833
Hence the rejection region will be all values greater than 1.833
Since 2.996 > 1.833, we will reject the Null Hypothesis.
