The speed of a boat in still water is 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 24 minutes is Choose the correct choice
A) 17.2 km B) 7.2 km C) 7.6 km D) 17.6 km E) 27.2 km

Rationale: "speed of a boat in still water = 15 km / hr speed of the current = 3 km / hr speed downstream = ( 15 + 3 ) = 18 km / hr distance travelled downstream in 24 minutes = ( 24 / 60 ) × 18 = ( 2 × 18 ) / 5 = 7.2 km answer is b"
Answer: B