A boat travels upstream from B to A and downstream from A to B in 3 hours. If the speed of the boat in still water is 9 km/hour and the speed of the current is 3 km/hour, the distance between A and B is  Choose the correct choice from the following
A) 4 km B) 8 km C) 6 km D) 12 km E) None of these
Let D is the distance travelled. Then,   12 km/(9+3) + 12 km/(9-3) = 3 =&gt; 12 km = 12   Answer: 12 km
<result>D</result>
A boat travels upstream from B to A and downstream from A to B in 3 hours. If the speed of the boat in still water is 9 km/hour and the speed of the current is 3 km/hour, the distance between A and B is