A man rows 750 m in 675 seconds against the stream and returns in 7 and half minutes. His rowing speed in still water is	Select the correct option:  A) 4 kmph  B) 5 kmph  C) 6 kmph  D) 7 kmph  E) None of these
Explanation:   Rate upstream = (750/675) = 10/9 m/sec   Rate downstream (750/450) m/sec = 5/3 m/sec   Rate in still water = (1/2)*[(10/9) + (5/3)] m/sec.   = 25/18 m/sec   = (25/18)*(18/5)= 
<gadget id="calculator">(25/18)*(18/5)</gadget>
<output>5</output>
5 kmph   Option 5 kmph
<result>B</result>
A man rows 750 m in 675 seconds against the stream and returns in 7 and half minutes. His rowing speed in still water is