A) 4km/h
B) 42 km/h
C) 50.4 km/h
D) 67.2 km/h
Correct Answer: C
Solution :
Let the length of the train be x metre. \[\therefore \] \[\frac{x+162}{18}=\frac{x+120}{15}=\] Speed of the train \[\Rightarrow \] \[\frac{x+162}{6}=\frac{x+120}{5}\] \[\Rightarrow \] \[6x+720=5x+810\] \[\Rightarrow \] \[x=810-720=90\] \[\therefore \] Speed of the train \[=\frac{90+162}{18}m/s\] \[=\frac{252}{18}\times \frac{18}{5}\text{km/h}=50.4\,\text{km/h}\]You need to login to perform this action.
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