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The Speed of an Ordinary Train is X Km per Hr and that of an Express Train is (X + 25) Km per Hr. (1) Find the Time Taken by Each Train to Cover 300 Km. (2) If the Ordinary Train Takes 2 Hr - Mathematics

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Question

The speed of an ordinary train is x km per hr and that of an express train is (x + 25) km per hr.
(1) Find the time taken by each train to cover 300 km.

(2) If the ordinary train takes 2 hrs more than the express train;calculate speed of the express train.

Solution

1) Speed of ordinary train = x km/hr

Speed of express train = (x + 25) km/hr

Distance = 300 km

We know

`"Time" = "Distance"/"Speed"`

∴ Time taken by ordinary train to cover 300 km = `300/x` hrs

Time taken by express train to cover 300 km  = `300/(x + 25)` hrs

2) Given that the ordinary train takes 2 hours more than the express train to cover the distance.

Therefore,

`300/x - 300/(x + 25) = 2`

`(300x + 7500 - 300x)/(x(x + 25)) = 2`

`7500 = 2x^2 + 50x`

`2x^2 + 50x - 7500 = 0`

`x^2 + 25x - 3750 = 0`

`x^2 + 75x - 50x - 3750 = 0`

x(x + 75) - 50(x + 75) = 0

(x + 75)(x - 50) = 0

x = -75, 50

But, speed cannot be negative. So, x = 50.
∴ Speed of the express train = (x + 25) km/hr = 75 km/hr

  Is there an error in this question or solution?
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APPEARS IN

 Selina Solution for Concise Mathematics for Class 10 ICSE (2020 (Latest))
Chapter 6: Solving (simple) Problems (Based on Quadratic Equations)
Exercise 6(C) | Q: 1 | Page no. 73
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The Speed of an Ordinary Train is X Km per Hr and that of an Express Train is (X + 25) Km per Hr. (1) Find the Time Taken by Each Train to Cover 300 Km. (2) If the Ordinary Train Takes 2 Hr Concept: Quadratic Equations.
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