Answer
2.5 times more intense
Work Step by Step
Given the magnitude equation $M = \log \frac{I}{S}$
with $S = 10^{-4}$
The question asks for how much more intense the 1995 Kobe earthquake (M = 7.2) was compared to the 1994 Northridge Earthquake (M = 6.8)
S is a constant that is already factored into the Magnitudes, so the $10^{-4}$ isn't necessary
$(7.2- 6.8) = \log I$
$10^{0.4} = {I}$
$I = 2.5$ times more intense