Question

an Express train takes 1 hour less than the passenger train to travel 132 kilometre between Mysore and Bangalore if the average speed of the express train is 11 km per hour more than the passenger train find the average speed of the two trains

Answer 1

Let the speed of passenger train be x km/hr
Hence speed of express train = (x +11) km/hr
Distance travelled by both the trains = 132 km
Time taken = (Distance)/(Speed)
Time taken by the passenger train = 132/x hrs
Time taken by the express train = 132/(x + 11) hrs

⇒132 × 11 = x(x + 11)
⇒x2+ 11x – 1452 = 0
⇒x2+ 44x – 33x – 1452 = 0
⇒x(x + 44) – 33(x + 44) = 0
⇒(x + 44)(x – 33) = 0
⇒(x + 44) = 0 or (x – 33) = 0
∴ x = –44 or x = 33
Since speed cannot be negative, x = 33
Thus the sped of passenger train is 33 km/hr and speed of express train is 44 km/hr.