A) 72 m
B) 54 m
C) 50 m
D) 45 m
Correct Answer: C
Solution :
Let the length of the train be x km and its speed be y km/h |
Speed of the train relative to first man |
\[=(y-2)km/h\] |
Speed of the train relative to second man |
\[=(y-4)km/h\] |
\[\therefore \] \[\frac{x}{(y-2)}=\frac{9}{(60\times 60)}\] |
and \[\frac{x}{(y-4)}=\frac{10}{(60\times 60)}\] |
\[\Rightarrow \] \[y-2=400x\] and \[y-4=360x\] |
\[\Rightarrow \]\[400x+2=360x+4\] |
\[\Rightarrow \] \[40x=2\] |
\[\Rightarrow \] \[x=\frac{1}{20}\text{km}\] |
\[=\left( \frac{1}{20}\times 1000 \right)\text{m}=50\,\,\text{m}\] |
\[\therefore \] Length of the train\[=50\,\,\text{m}\] |
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