BOATS and STREAMS Q11

11.      A boat takes 19 hours for travelling downstream from point A to point B and coming back to a point C midway between A and B. If the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph, what is the distance between A and B ?

             A.  160 km B.  180 km

            C.  200 km   D.  220 km

Answer:

Speed Downstream	= (14 + 4) km/hr
	= 18 km/hr.
Speed upstream	=(14 - 4) km/hr
	= 10 km/hr..
Let the distance b/w A and B be xkm.Then	=(x/18+ x/2 / 10)
	= 19
	= 19x / 180 = 19
	x= 180.