The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is:

Answer: Option D

Speed downstream
= (15 + 3) kmph
= 18 kmph
Distance travelled
= $$\left(18\times \frac{12}{60}\right)$$   km
= 3.6 km