A man rows to a place 35 km in distance and back in 10 hours 30 minutes. He found that he can row 5 km with the stream in the same time as he can row 4 km against the stream. Find the rate of flow of the stream.
Answer & explanation
Correct answer: option 4
If time is same, then ratio of distance = ratio of speed
(D.S) Downstream : (U.S) upstream
Distance 5R : 4R
Speed 5R : 4R
ATQ, \(\frac{35}{5R}\) + \(\frac{35}{4R}\) = 10\(\frac{1}{2}\) hrs
\(\frac{35 × 9R}{20 R^2}\) = \(\frac{21}{2}\)
R = 1.5
Speed of stream = \(\frac{5R - 4R}{2}\) × 1.5 = 0.75 km/hr