A 014-Km Wide River Flows with a Uniform Speed of 4

Multiple Choice

A 0.14-km wide river flows with a uniform speed of 4.0 m/s toward the east. It takes 20 s for a boat to cross the river to a point directly north of its departure point on the south bank. What is the speed of the boat relative to the water?

A) 5.7 m/s
B) 8.5 m/s
C) 8.1 m/s
D) 7.0 m/s
E) 6.4 m/s