A) 384km/h
B) 370km/h
C) 368 km/h
D) None of these
Correct Answer: A
Solution :
[a] Let each side of the square be x km and let the average speed of the plane around the field be y km/h. Then, \[\frac{x}{200}+\frac{x}{400}+\frac{x}{600}+\frac{x}{800}=\frac{4x}{y}\] \[\Rightarrow \,\,\,\frac{25x}{2400}=\frac{4x}{y}\Rightarrow y=\left( \frac{2400\times 4}{25} \right)=384.\] \[\therefore \]Average speed = 384 km/h.You need to login to perform this action.
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