Answer: [tex]24^{\circ}[/tex]
Step-by-step explanation:
Given
River is flowing from south to North with a velocity of [tex]u=1\ m/s[/tex]
Motor boat traverses the river from east to west at a speed of [tex]v=2.5\ m/s[/tex]
South component of boat velocity must compensate the river velocity in order to travel in west direction.
[tex]\therefore v\sin \theta=u\\\\\Rightarrow 2.5\sin \theta=1\\\\\Rightarrow \sin \theta=\dfrac{2}{5}\\\\\Rightarrow \theta=23.57^{\circ}\approx 24^{\circ} \text{south of west}[/tex]