After traveling a distance of 60 km train meets with an accident and its speed becomes 3/4th of its actual speed and reaches 35 minutes late. If this accident had occurred after traveling 20 km more train would have reached the station 25 minutes late. Find the initial speed (in km/hr) of train.

40

Let initial speed = x km/hr

decreased speed = \(\frac{3x}{4}\) km/hr

If this accident had occurred after travelling 20 km more this means speed of train in that 20 km also is x km/hr instead of \(\frac{3x}{4}\) km/hr and that makes a difference of  ( 35 - 25 ) = 10 min in time taken .

\(\frac{20 \;× \;4}{3x}\)   -  \(\frac{20}{x}\)  = \(\frac{20}{60}\)  

\(\frac{80 \;- \;60}{3x}\)   =  \(\frac{20}{60}\)    

x = 40 

So , initial speed of train = 40 km/hr