We often speak of the "root mean square" or rms displacement of a diffusing object in order to quantify the average distance a diffusing particle moves in a given amount of time. This rms displacement is simply given by the square root of the average of the square of the displacement. Considering again how the average of the square of the displacement varies with time in the diffusion displacement equation, if a particle, on average, diffuses 1.0 mm in one hour, how long (in hours) will it take for the particle to diffuse 9 mm (on average)