Question

A passenger train takes 1 hr more than an express train to travel a distance of 240 km from Chennai to Virudhachalam.

The speed of passenger train is less than that of an express train by 20 km per hour. find the average speed of both trains​

Answer 1

Answer:

answere can be 120 km per hour

Answer 2

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☞ The average speed of both the trains is 68.57 km/h

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$\huge\sf\blue{Given}$

✭ The distance is 240 km

✭ Passenger train takes 1 hour more than the express train

✭ Passenger train is 20 km/h slower than the express train

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• Their average speed?

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☆ Let the time taken by the express train be x hour

☆ The time taken by the passenger train (x + 1) hour

Find the speed taken for the express train:

➝ Speed = Distance ÷ Time

➝ Speed = 240/x km/h

Find the speed taken for the passenger train:

➝ Speed = Distance ÷ Time

➝ Speed = 240/(x + 1) km/h

Solve x:

Given that the passenger train is 20 km/h slower

➝ 240/x - 240/(x + 1) = 20

➝ 240/x - 240/(x + 1) = 20

➝ 240(x + 1) - 240x = 20x(x + 1)

➝ 240x + 240 - 240x = 20x² + 20x

➝ 20x² + 20x - 240 = 0

➝ 20(x - 3)(x + 4)  = 0

➝ x = 3 or x = -4 (rejected, since time cannot be negative)

Find the time taken:

Express train = x hours

Express train = 3 hours

Passenger train = x + 1 hours

Passenger train = 3 + 1 hours

Passenger train = 4 hours

Find the average speed:

Average Speed = Total Distance ÷ Total Time

➝ Average Speed = (2 x 240)  ÷ (3 + 4)

➝ Average Speed = 480 ÷ 7

➝ Average Speed = 68.57 km/h

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