Question

A bus travels 300 kilometers at a given speed. If the speed is increased by 5 kilometers per hour, the trip will be reduced by two hours. Find the speed.

Answer 1

25km/hr (take the word train as bus )

Explanation:

Answer

Let x km/hr be the constant speed of the train,

Then Time taken to cover 300km=

x

300

hrs

Time taken to cover 300km when the speed is increased by 5km/hr=

x+5

300

hours

It is given that the time to cover 300km is reduced by 2 hours

∴

x

300

−

x+5

300

=2

⇒

x(x+5)

300(x+5)−300x

=2⇒2x

2

+10x=1500

⇒x

2

+5x−750=0⇒x

2

+30x−25x−750=0

⇒(x+30)(x−25)=0⇒x=25orx=−30

But x cannot be negative. Therefore x=25

Hence, the original speed of the train is 25km/hr