Question

a train takes 2 hours less for a journey of 300km if its speed is increased by 5km/hr from its usual speed .find the usual speed of the train.

Answer 1

distance=300km
time less taken=2hr
speed=d/t=300/2=150
150+5=155km/hr

Answer 2

Answer:

Let the usual speed of the train be y km / hr .

A.T.Q.

$\displaystyle{\frac{300}{y} -\frac{300}{y+5} =2 }$

300 ( y + 5 ) - 300 y = 2 y ( y + 5 )

y² + 5 y - 750 = 0

y² + 30 y - 25 y - 750 = 0

( y + 30 ( y -25 ) = 0

y = - 30 or y = 25

Since , speed of train can't be negative .

Therefore , the usual speed of the train is 25 km / hr .