A man can row 9 1/3 kmph in still water and finds that it takes him thrice as uch time to row up than as to row down the same distance in the river. The speed of the current is: Select.
A) 3 1/2 km/hr
B) 2 1/3 km/hr
C) 4 1/2 km/hr
D) 4 2/3 km/hr
E) None
Sol.   Let speed upstream be x kmph. Then, speed downstream = 3x kmph.   Speed in still water = 1/2(3x + x) kmph = 2x kmph.   ∴ 2x = 28/3 ⇒ x = 14/3   So, Speed upstream = 14/3 km/hr; Speed downstream = 14/hr.   Hence, speed of the current = 1/2 [14 - 14/3] km/hr = 14/3 km/hr = 4 2/3 km/hr.   Answer 4 2/3 km/hr
<result>D</result>
A man can row 9 1/3 kmph in still water and finds that it takes him thrice as uch time to row up than as to row down the same distance in the river. The speed of the current is: