A) 35 km/hour
B) \[33\frac{1}{3}\] km/hour
C) 30 km/hour
D) \[37\frac{1}{12}\] km/hour
Correct Answer: B
Solution :
Let the total distance be \[x\] km. Total time\[\begin{align} & \,\,\,\,\,\,\underline{x\,}\,\,\,\,\,\,\,\,\,\underline{x\,}\,\,\,\,\,\,\underline{5x} \\ & =\frac{3}{25}+\frac{4}{30}+\frac{12}{50} \\ \end{align}\] \[=\frac{x}{75}+\frac{x}{120}+\frac{x}{120}\] \[=\frac{x}{75}+\frac{x}{60}=\frac{4x+5x}{300}=\frac{3x}{100}\] hours \[\therefore \] Average speed \[=\frac{Total\,\,dis\tan ce}{Time\,\,taken}\] \[=\frac{x}{\frac{3x}{100}}=\frac{100}{3}=33\frac{1}{3}\] kmp
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