Question

A man rows to a place 48 km distant and 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. 1km/h
• B. 1.5km/h
• C. 1.8km/h
• D. 3.5km/h

Answer 1

The Correct Option is A

The correct option is (A):Speed of man = \(x\) km/hr
Speed of boat = \(y\) km/hr
Downstream speed = \((x+y)\)km/hr and  Upstream speed = \((x-y)\)km/hr
Accordingly \(\frac{4}{x+y}\)=\(\frac{3}{x-y}\)
\(4x-4y=3x=3y\) 
i.e. \(x=7y\) -----(1)
\(\frac{48}{x+y}+\frac{48}{x-y}= 14\)
\(\frac{48}{8y}+\frac{48}{6y}= 14\)
\(y=1\)
\(\therefore\) Speed of stream 1km/hr