A man travelled a certain distance by train at the rate of 25 kmph. and walked back at the rate of 4 kmph. If the whole journey took 5 hours 48 minutes, the distance was:

A man travelled a certain distance by train at the rate of 25 kmph. and walked back at the rate of 4 kmph. If the whole journey took 5 hours 48 minutes, the distance was:
[A]15 km
[B]20 km
[C]25 km
[D]30 km

20 km
Let the distance be x km.
Total time = 5 hours 48 minutes
= 5+\frac{48}{60} = \left ( 5+\frac{4}{5} \right )hours
= \frac{29}{5}hours
\therefore \frac{x}{25}+\frac{x}{4} = \frac{29}{5}
=> \frac{4x+25x}{100} = \frac{29}{5}
=> 5\times 29x = 29\times 100
=> x = \frac{29\times 100}{5\times 29} = 20km.
Hence option [B] is the right answer.

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