RRB NTPC Mains or Stage 2 Model Paper 8 with solutions

(d) Let the speed of the second train be x km/h
The relative speed = (50 + x) km/h
These trains will cross each other in a time equivalent of covering a distance equal to 108 + 112, i.e. 220 meters in 6 seconds,running a speed of (50 + x) km/h
∴$\frac{1}{50+\mathit{x}}\times \frac{220}{1000}=\frac{6}{3600}\Rightarrow \mathit{x}=82$
∴The speed of the second train = 82 km/h.