A) 40 km/hr
B) 80 km/hr
C) \[46\frac{2}{3}\] km/hr
D) 36 km/hr
Correct Answer: D
Solution :
Average speed\[=\frac{\text{Total distance }}{\text{Total time}}\]\[=\frac{x}{{{t}_{1}}+{{t}_{2}}}\] \[=\frac{x}{\frac{x/3}{{{v}_{1}}}+\frac{2x/3}{{{v}_{2}}}}\]\[=\frac{1}{\frac{1}{3\times 20}+\frac{2}{3\times 60}}=36\ km/hr\]
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