A boat covers a certain distance downstream in 1 hour, while it comes back in 11â„2 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water? Answers
A) 31 kmph  B) 16 kmph  C) 19 kmph  D) 15 kmph  E) 14 kmph
Let the speed of the water in still water =x   Given that speed of the stream = 3 kmph   Speed downstream =(x+3) kmph   Speed upstream =(xâˆ’3) kmph   He travels a certain distance downstream in 1 hour and come back in 11â„2 hour.   i.e., distance travelled downstream in 1 hour = distance travelled upstream in 11â„2 hour   Since distance = speed Ã— time, we have   (x+3)Ã—1=(x-3)3/2   2(x+3)=3(x-3)   2x+6=3x-9   x=6+9= 
<gadget id="calculator">6+9</gadget>
<output>15</output>
15 kmph   Answer: 15 kmph
<result>D</result>
A boat covers a certain distance downstream in 1 hour, while it comes back in 11â„2 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?