Trains Boats and Streams Practice Test 4 with solutions

Let the rate of current = x km/hour
According to the question,
$\frac{32}{12-\mathit{x}}-\frac{32}{12+\mathit{x}}$ = 2
= $\frac{1}{12-\mathit{x}}-\frac{1}{12+\mathit{x}}$ = $\frac{1}{16}$
= $\frac{12+\mathit{x}-12+\mathit{x}}{144-{\mathit{x}}^2}$ = $\frac{1}{16}$
${\mathit{x}}^2$ + 32x - 144 = 0
${\mathit{x}}^2$ + 36x - 4x - 144 = 0
(x + 36) (x - 4) = 0
x = 4 km/hour
Downstream speed of the boat = 12 + 4
= 16 km/hour