​Speed of a boat in still water is 27 km/hr and speed of river flow is 9 km/hr. If boat rows at angle 150° with the river flow ​

Question

Speed of a boat in still water is 27 km/hr and speed of river flow is 9 km/hr. If boat rows at angle \(150^\circ\) with the river flow and it takes 30 seconds to cross the river. Find with of the river. 

(1) 56 m 

(2) 100 m 

(3) 225 m 

(4) 112.5 m

Answer 1

Correct option is: (4) 112.5 m

\(V_y = 27 \times \frac{1}{2} \ \text{km/h}\)

\(W = \frac{27}{2} \times \frac{5}{18} \times 30\)

\(W = 112.5 \ m\)