Trains Boats and Streams Practice Test 3 with solutions

Let x km/hr and y km/hr be the speeds of the boat in still water and the speed of the current respectively, then
$\frac{24}{\mathit{x}-\mathit{y}}+\frac{36}{\mathit{x}+\mathit{y}}$ = 6
⇒ $\frac{4}{\mathit{x}-\mathit{y}}+\frac{6}{\mathit{x}+\mathit{y}}$ = 1 ... (i)
And, $\frac{36}{\mathit{x}-\mathit{y}}+\frac{24}{\mathit{x}+\mathit{y}}$ = $\frac{13}{2}$ ... (ii)
Solving these two equations, we get
x + y = 12; x – y = 8
Hence, y = $\frac{1}{2}\left(12-8\right)$ = 2 km/hr