Answer:
Step-by-step explanation:
Relative to the water, the boat is moving
10sin30 = 5 mph N
10cos30 = 8.66 mph E
As the water is flowing 4 mph south, the net boat north velocity is 5 - 4 = 1 mph relative to shore
So relative to shore, the boat appears to be moving
v = √(1² + 8.66²) = √76 = 8.71779... 8.7 mph
θ = arctan(1/8.66) = 6.58677... 6.6° N of E