A train covers a distance of 90 km with a speed of 120 km per hour and covers another a distance of 40 km with a speed of 60 km per hour find its average speed.
Answers
Answered by
1
Answer:
Let original speed =xkm/hr
⇒ Time taken to travel =
x
90
hr
⇒ New speed =(x+15)km/hr
⇒ Time taken to travel =
x+15
90
hr
∴
x
90
=
x+15
90
+
2
1
⇒
x
90
−
x+15
90
=
2
1
⇒ 90(
x
1
−
x+15
1
)=
2
1
⇒
x(x+15)
x+15−x
=
180
1
⇒ 15×180=x(x+15)
⇒ 2700=x
2
+15x
⇒ x
2
+15x−2700=0
⇒ x
2
+60x−45x−2700=0
⇒ x(x+60)−45(x+60)=0
⇒ (x+60)(x−45)=0
Speed can not be negative.
∴ The original speed of the train is 45km/hr
Similar questions
English,
5 hours ago
Social Sciences,
9 hours ago
English,
9 hours ago
Hindi,
7 months ago
History,
7 months ago