Rajdhani train covered the distance between Lucknow and Delhi at a uniform speed. It is observed that if rajdhani would have run slower by 10 km/hr,it would have taken 3 hours more to reach the destination and if rajdhani would have run faster by 10 km/hr,it would have taken 2 hours less. Find the distance Lucknow and Delhi?
Answers
Answer:
Consider the speed of train as x
and the time taken by train as y
As we know: Distance(D) = Speed × Time
then Distance will be x × y = xy
Now,
If Rajdhani would have run slower by 10 km/h it will be (x-10)
It would have taken 3 hrs more to reach destination it will be (y+3)
1st Equation is
(x-10) (y+3) = xy
xy+3x-10y-30 = xy (xy will be canceled on both sides)
then the eq. will be;
3x-10y-30 = 0 ⇒ 1st Equation
If Rajdhani would have run faster by 10km/h it will be (x+10)
it would have taken 2hrs less it will be (y-2)
2nd Equation is
(x+10) (y-2) = xy
xy-2x+10y-20 = xy (xy will be canceledon both sides)
-2x+10y-20 = 0 ⇒ 2nd Equation
For further solution Add these 2 equation:
3x -10y-30 = 0
-2x+10y-20 = 0
------------------------
x-50 = 0
therefore x= 50 (hence uniform speed of train is 50)
For the value of y apply the value of x on 1st equation::
3x - 10y - 30 = 0
3 × 50 - 10y - 30 = 0
150 -10y -30 = 0
120 - 10y = 0
-10y = -120
∴ y= 12 (average time taken by rajdhani to reach destination.
Distance = speed × time
50 × 12 = 600 Km
∴ The distance between Lucknow to Delhi is 600 Km.
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