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A motorcyclist completes a certain journey in 5 hours. He covers one-third distance at 60 km/hr and the rest at 80 km/hr. The length of the journey is :
Answer & Solution
Correct Answer:
Option
D
Let the length of the journey be x km.
Then,
$$\eqalign{ & \Rightarrow \frac{{\frac{1}{3}x}}{{60}} + \frac{{\frac{2}{3}x}}{{80}} = 5 \cr & \Rightarrow \frac{x}{{180}} + \frac{x}{{120}} = 5 \cr & \Rightarrow \frac{{5x}}{{360}} = 5 \cr & \Rightarrow x = 360\,\text{ km} \cr} $$
Then,
$$\eqalign{ & \Rightarrow \frac{{\frac{1}{3}x}}{{60}} + \frac{{\frac{2}{3}x}}{{80}} = 5 \cr & \Rightarrow \frac{x}{{180}} + \frac{x}{{120}} = 5 \cr & \Rightarrow \frac{{5x}}{{360}} = 5 \cr & \Rightarrow x = 360\,\text{ km} \cr} $$
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