A train travels 480 km at a uniform speed.If the speed had been 10km/h more,it would have taken 4 hours less for the some journey, find the speed of the train?
Answers
Answered by
8
Let the speed of the train be x km/hr. Then
Time taken to travel a distance of 480km=
x
480
hr
Time taken by the train to travel a distance of 480km with the speed (x−8)km/hr=
x−8
480
hr
It is given that if the speed had been 8km/hr less, then the train would have taken 3 hours more to cover the same distance
∴
x−8
480
=
x
480
+3
⇒
x−8
480
−
x
480
=3⇒
x(x−8)
480(x−x+8)
=3⇒
x(x−8)
480×8
=3
⇒3x(x−8)=480×8⇒x(x−8)=160×8⇒x
2
−8x−1280=0
This is the required quadratic equation.
Answered by
2
Answer:
Let the speed of the train be x km/hr. Then
Time taken to travel a distance of 480km=
x
480
hr
Time taken by the train to travel a distance of 480km with the speed (x−8)km/hr=
x−8
480
hr
It is given that if the speed had been 8km/hr less, then the train would have taken 3 hours more to cover the same distance
∴
x−8
480
=
x
480
+3
⇒
x−8
480
−
x
480
=3⇒
x(x−8)
480(x−x+8)
=3⇒
x(x−8)
480×8
=3
⇒3x(x−8)=480×8⇒x(x−8)=160×8⇒x
2
−8x−1280=0
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