The Distance, in Miles, from Me to a Moving Train $D ( t ) = \sqrt { ( 30 t ) ^ { 2 } + ( 5 - 30 t ) ^ { 2 } }$

Multiple Choice

The distance, in miles, from me to a moving train is given by $D ( t ) = \sqrt { ( 30 t ) ^ { 2 } + ( 5 - 30 t ) ^ { 2 } }$ Here represents hours since I heard the train whistle. Calculate the distance to the train 7 hours after I heard the whistle.

A) 5 miles
B) 293.47 miles
C) 86125 miles
D) 208.55 miles