Solve the Problem $d$ , One Can See from an Airplane to the Horizon

Solve the problem.
-A formula for calculating the distance, $d$ , one can see from an airplane to the horizon on a clear day is $\mathrm { d } = 1.22 \mathrm { x } ^{1 / 2}$ , where $\mathrm { x }$ is the altitude of the plane in feet and $\mathrm { d }$ is given in miles. How far can one see in a plane flying at 18,000 feet? Round your answer to the nearest tenth mile, if necessary.

A) $163.7 \mathrm { mi }$
B) $1098 \mathrm { mi }$
C) $148.2 \mathrm { mi }$
D) $10,980 \mathrm { mi }$