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? Answers
A) 14 kmph
B) 12 kmph
C) 18 kmph
D) 1 kmph
E) none of these

Rationale: explanation : let man ' s rate upsteam be x kmph then his rate of downstream = 3 x kmph rate still water = 1 / 2 ( 3 x + x ) = 2 x 2 x = 36 x = 18 rate of upstream = 18 rate of downstream = 54 rate of stream 1 / 2 ( 54 - 18 ) = 18 kmph answer : option c
Answer: C