A man traveled from the village to the post-office at the rate of 25 kmph and walked back at the rate of 4 kmph. If the whole journey took 5 hours 48 minutes, find the distance of the post-office from the village ?
Choose one:
A) 70 m B) 80 km C) 20 km D) 10 km E) 73 km

Rationale: explanation : average speed = , here a = 25 b = 4 = 2 x 25 x 4 / ( 25 + 4 ) = 200 / 29 km / hr . distance covered in 5 hours 48 minutes = speed x time = ( 200 / 29 ) x ( 29 / 5 ) distance covered in 5 hours 48 minutes = 40 kms . distance of the post office from the village = ( 40 / 2 ) = 20 km . answer : c
Answer: C