Answer
1.11 m of snow
Work Step by Step
The paratrooper as a mass of 85kg and has an initial speed of 56m/s. Since the survivable limit is 1.2 x 10^5 N then his acceleration (using F = ma) is a = 1412 $m/s^2$.
To find the depth of snow that this would take, we use
$v^2 = v_{0}^2 + 2a\Delta x $ where v0 = 56 m/s and v = 0 and we solve for $Delta x$
We find that $\Delta x = 1.11 m$ of snow
