Problem $38$: Find the time $($in years$)$ it takes for a molecule of water to move from a factory to a bore hole located $2$ miles away in a homogeneous silty sand unconfined aquifer with a hydraulic conductivity of $K=15{10}^{-5}$ in$/$sec$,$ an effective porosity of $0\mathrm{.}42$ and observing that the water table drops $30ft$ from the factory to the bore hole.

$($A$)40$

$($B$)400$

$($C$)4000$

$($D$)40000$