Traveling at 50 km/h, a person reaches his destination in a certain time.  He covers 80% of his journey in \(\frac{3}{5}\)th of the time.  At what speed (km/h) should he travel to cover the remaining journey so that he reaches the destination right on time?

25

Let, Distance = 500 km

Speed = 50 km/h

Time = \(\frac{500}{50}\) = 10 hours

500 × 80% = 400, remaining = 500 - 400 = 100

Remaining distance is covered in \(\frac{2}{5}\)th of time.

Speed = \(\frac{100}{\frac{2}{5} × 10}\) = \(\frac{100}{4}\) = 25 km/h