A sailor takes thrice as much time as row to B from A against the current as he takes along the current to A from B. If he rows at the rate of 10 km/hr in still water, then what will be the rate of current?
Answer & explanation
Correct answer: option 1
If distance is same, then ratio of speed = \(\frac{1}{ratio\;of\;'time}\)
Downstream(D.S) : Upstream(U.S)
Time 1 : 3
speed 3 : 1
Then, ratio of speed of boat and current = \(\frac{3\;+\;1}{2}\) : \(\frac{3\;-\;1}{2}\)
= 2 : 1
5x ⇓ ⇓ x5
(given) 10 km/hr 5 km/hr