Indian Institute of Foreign Trade 2016 Solved Paper

(a) According to question,

Let the distance between Delhi and Noida is x km.
Let they first meet at point A after one hour.
Distance covered by Shruti = 2x – d
Distance covered by Krishna = d
∴ Ratio of speeds of Shruti and Krishna is 2x – d : d ...(i)
Let next they meet at B after half an hour. As Krishna covered distance ‘d’ in one hour, so he will cover distance $\frac{\prime \mathrm{d}\prime }{2}$ in half an hour ∴ AB = $\frac{\mathrm{d}}{2}$
Distance covered by Shruti in second meeting
= $\mathit{x}-\mathit{d}+\left(\mathit{x}-\frac{3\mathit{d}}{2}\right)=2\mathit{x}-\frac{5\mathit{d}}{2}$

∴Ratio of speeds of Shruti and Krishna is
$2\mathit{x}-\frac{5\mathit{d}}{2}:\frac{\mathit{d}}{2}$ ...(ii)
$\frac{2\mathit{x}-\mathit{d}}{\mathit{d}}=\frac{2\mathit{x}-\frac{5\mathit{d}}{2}}{\frac{\mathit{d}}{2}}\Rightarrow 2\mathit{x}-\mathit{d}=4\mathit{x}-5\mathit{d}$
$\Rightarrow 2\mathit{x}=4\mathit{d}\Rightarrow \mathit{x}=2\mathit{d}$
Now Krishna covered distance ‘d’ in one hour, so he will cover distance between Delhi to Noida in 2 hours.