A) \[14\frac{2}{5}\text{km/h}\]
B) 15 km/h
C) \[15\frac{1}{2}\text{km/h}\]
D) 16 km/h
Correct Answer: A
Solution :
Average speed \[=\left( \frac{2xy}{x+y} \right)\,\,\text{km/h}\] \[=\left( \frac{2\times 12\times 18}{12+18} \right)\text{km/h}\] \[=\left( \frac{2\times 12\times 18}{30} \right)\text{km/h}\]\[=14\frac{2}{5}\,\,\text{km/h}\]You need to login to perform this action.
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