A man can row 4 kmph is still water. If the river is running at 2 kmph it takes 90 min to row to a place and back. How far is the place Choose one.
A) 2 km  B) 4 km  C) 5 km  D) 2.25 km  E) None of these
Explanation :   Speed in still water = 4 kmph   Speed of the stream = 2 kmph   Speed upstream = (4-2)= 
<gadget id="calculator">(4-2)</gadget>
<output>2</output>
2 kmph   Speed downstream= (4+2)= 
<gadget id="calculator">(4+2)</gadget>
<output>6</output>
6 kmph   Total time= 90 minutes = 90⁄60 hour = 3⁄2 hour   Let L be the distance. Then   (L/6) + (L/2) = 32   =&gt; L + 3L = 9   =&gt; 4L = 9   =&gt; L = 9⁄4= 2.25 km. Answer : Option 2.25 km
<result>D</result>
A man can row 4 kmph is still water. If the river is running at 2 kmph it takes 90 min to row to a place and back. How far is the place