RRB NTPC 17 January 2017 Paper

(2) Speed of Vishnu = 10 km/h ,8km/h, 30km/h
Let the distance be x.
So, total distance = x + x + x = 3x
Total time = 15.5 minutes =$\frac{155}{600}$hours
Time taken by Vishnu at 10 km/h
=$\frac{\mathit{D}}{\mathit{S}}$=$\frac{\mathit{x}}{10}$........(i)
Similarly, at 8 km/h =$\frac{\mathit{x}}{8}$........(ii)
And 30 km/h =$\frac{\mathit{x}}{30}$........(iii)
According to the question,
$\mathit{x}10+\mathit{x}8+\mathit{x}30=\frac{155}{600}$
$\Rightarrow \frac{12\mathit{x}+15\mathit{x}+4\mathit{x}}{120}=\frac{155}{600}$
$\Rightarrow 31\mathit{x}=31$
$\Rightarrow \mathit{x}=1$
Total distance $=3\mathit{x}=3\mathit{k}\mathit{m}$