A man can row 9 1 3 kmph in still water and finds that it takes him thrice as much time to row up th......

A man can row 9 (1/3) kmph in still water and finds that it takes him thrice as much time to row up than as to row down the same distance in the river. What is speed of the current ?

Let man’s rate upstream be x km/hr. Then his rate downstream is 3 x km/hr
Given:
Speed in still water = 9 (1/3) = 28/3 km/hr
i.e, ½ (a+b) = 28/3 km/hr
½ (x+3x) = 28/3
2x = 28/3    x = 28/ 2 x 3 = 14/3 km/hr
rate upstream b = 14/3 km/hr and
rate downstream a = 14/3 x 3 = 14 km/hr
speed of the current = ½ (a-b) = ½ (14 – 14/3)
= ½ (42-14/3) = 28/6 = 4 (2/3) km/h

By: Manpreet kaur