DATE
PAGE
A train travell on a 120 km Journey
it covers 90 km with a speed of 30 km per hour and
the remaining distance with the
Speed of 6o km per hour find its
average speed
Answers
Answered by
1
Step-by-step explanation:
MATHS
A train covers a distance of 90 km at a uniform speed. Had the speed been 15 km/hour more, it would have taken 30 minutes less for the journey. The original speed of the train is ----- km/hr.
November 22, 2019avatar
Akhil Narbekar
SHARE
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