Question

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

Answer 1

Let the usual speed of the passenger train be. Then,

Increased speed of the passenger train

Time taken by the train under usual speed to cover

Time taken by the train under increased speed to cover

Therefore,

So, either

Or

But, the speed of the passenger train can never be negative.

Hence, the usual speed of passenger train is