A) 500 kmph
B) 480 kmph
C) 384 kmph
D) 395 kmph
Correct Answer: C
Solution :
[c] Let each side be x km. so that total distance to be travelled = 4x \[\Rightarrow \]Total time \[=\frac{x}{200}+\frac{x}{400}+\frac{x}{600}+\frac{x}{800}\] \[=\frac{25x}{2400}\] Let y be the average speed. \[\therefore \,\,\frac{4x}{y}=\frac{25x}{2400}\,\,so\,\,y=2400\times \frac{4}{25}=384.\]You need to login to perform this action.
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