Question

A man rows to a place 48 km distant and comes back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. The rate of the stream is ............

• A. 0.5 km/hr
• B. 1 km/hr
• C. 3.5 km/hr
• D. 1.8 km/hr

Answer 1

Answer: (B)

1 km/hr

Suppose he move 4 Km downstream in x hours.Then
Speed downstream=$\frac{4}{n}$Km\hr
Speed upstream=$\frac{3}{n}$Km\hr
$\therefore \frac{48}{\$\frac{4}{n}\$}+\frac{48}{\frac{3}{x}}=14$
$\frac{48x}{4}+\frac{48x}{3}=14$
Or x=$\frac{336}{168}=2$
So spead downstream=$\frac{4}{\frac{1}{2}}=8$Km\hr
Or speed upstream =$\frac{3}{\frac{1}{2}}=6$Km\hr
So rate of stream =$\frac{1}{2}(8-6)=\frac{2}{2}=1$Km\hr