A man can row 7.5 kmph in still water and he finds that it takes him twice as long to row up as to row down the river. Find the rate of stream. Choose the correct choice from the following options.
A) 2.5 km/hr  B) 12.5 km/hr  C) 1 2.6 km/hr  D) 22.5 km/hr  E) 22.6 km/hr
Given that, time taken to travel upstream = 2 × time taken to travel downstream   When distance is constant, speed is inversely proportional to the time   Hence, 2 × speed upstream = speed downstream   Let speed upstream = x   Then speed downstream = 2x   we have, 1/2(x+2x) = speed in still water   ⇒1/2(3x)=7.5   3x = 15   x = 5   i.e., speed upstream = 5 km/hr   Rate of stream = 1/2(2x−x)=x/2=5/2= 
<gadget id="calculator">5/2</gadget>
<output>5/2 = around 2.5</output>
2.5 km/hr   2.5 km/hrnswer is 2.5 km/hr
<result>A</result>
A man can row 7.5 kmph in still water and he finds that it takes him twice as long to row up as to row down the river. Find the rate of stream.