Answer
Will Power had a more convincing victory.
Work Step by Step
$z=\frac{x-μ}{σ}$
Dario Franchitti:
$z=\frac{185.62-186.15}{0.359}=-1.48$
Will Power:
$z=\frac{112.57-112.8}{0.131}=-1.76$
Will Power had a more convincing victory. His z-score is more negative than Dario Franchitti's z-score.
