# The distance between Mumbai and Pune is 192 km. Travelling by the Deccan Queen, it takes 48 minutes less than another train. Calculate the speed of the Deccan Queen if the speeds of the two trains differ by 20 km/hr.

Let the speed of Deccan Queen be x km/h

Speed of another train = (x – 20)km/h

According to the question   taking LCM  4800 = x2 – 20x cross multiplying

x2 – 20x – 4800 = 0

Using the splitting middle term – the middle term of the general equation is divided in two such values that:

Product = a.c

For the given equation a = 1 b = – 20 c = – 4800

= 1. – 4800 = – 4800

And either of their sum or difference = b

= – 20

Thus the two terms are – 80 and 60

Difference = – 80 + 60 = – 20

Product = – 80.60 = – 4800

x2 – 80x + 60x – 4800 = 0

x(x – 80) + 60(x – 80) = 0

(x – 80) (x + 60) = 0

x = 80 or x = – 60 (but x cannot be negative)

Hence the speed of Deccan Queen is 80 km/hr

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos  Get To Know About Quadratic Formula42 mins  Quiz | Knowing the Nature of Roots44 mins  Take a Dip Into Quadratic graphs32 mins  Foundation | Practice Important Questions for Foundation54 mins  Nature of Roots of Quadratic Equations51 mins  Getting Familiar with Nature of Roots of Quadratic Equations51 mins  Quadratic Equation: Previous Year NTSE Questions32 mins  Champ Quiz | Quadratic Equation33 mins  Balance the Chemical Equations49 mins  Understand The Concept of Quadratic Equation45 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation view all courses 