NCHMCT JEE 2016 Question Paper with solutions for online practice

Let, the speed of the motorboat = x km/hr
According to the question,
$\frac{6}{\mathit{x}+2}+\frac{6}{\mathit{x}-2}$ = $\frac{33}{60}$
⇒ $\frac{6\left(\mathit{x}-2+\mathit{x}+2\right)}{\left(\mathit{x}-2\right)\left(\mathit{x}+2\right)}$ = $\frac{11}{20}$
⇒ 12x × 20 = $11{\mathit{x}}^2$ - 11 × 4
⇒ $11{\mathit{x}}^2$ - 240x - 44 = 0
⇒ $11{\mathit{x}}^2$ - 242x + 2x - 44 = 0
⇒ 11x (x - 22) + 2 (x - 22) = 0
⇒ (x - 22) (11x + 2) = 0
∴ x = 22
speed of the motorboat = 22 km/hr.