Question

A train covers a distance of 300 km at a uniform speed. If the speed of the train is
increased by 5 km/hour, it takes 2 hours less in the journey. Find the original speed of
the train.
[All India]​

Answer 1

Answer:

distance=d=300km ...Given

Let the time taken to cover the distance be t and speed be x km/hr.

Speed =

time

distance

=

t

300

=x .....(1)

At increased speed,

⇒x+5=

t−2

300

...(2)

Substituting eq. (1) in eq.(2), we get

⇒

t

300

+5=

t−2

300

⇒(300+5t)(t−2)=300t

⇒300t−600+5t

2

−10t=300t

⇒5t

2

−10t−600=0

∴t

2

−2t−120=0

∴t

2

−12t+10t−120=0

∴t(t−12)+10(t−12)=0

∴(t−12)(t+10)=0

∴t=12 or t=−10

∵t cannot be negative, t=12hrs

∴ Original speed =

12

300

=25km/hr.