A man can row 36 kmph in still water. It takes him thrice as long to row up as to row down the river. Find the rate of the stream? Choose the most appropriate option:
A) 14 kmph B) 12 kmph C) 18 kmph D) 1 kmph E) None of these
Explanation:   Let man's rate upsteam be X kmph   Then his rate of downstream = 3X kmph   Rate still water = 1/2 (3X + X) = 2X   2X = 36   X = 18   Rate of upstream = 18   Rate of downstream = 54   Rate of stream 1/2 ( 54 - 18) = 18 kmph   Answer: Option 18 kmph
<result>C</result>
A man can row 36 kmph in still water. It takes him thrice as long to row up as to row down the river. Find the rate of the stream?