Question

on a 80 km track a train travel 40 km with uniform speed of 30 km / hr the need 40 km. it travel with a uniform speed of 20 km / hr . what is the average speed of train during the entire journey .​

Answer 1

Answer:

24 km/h

Explanation:

As per the provided information in the given question, we have :

• Total length of the track = 80 km
• Speed attained to cover first 40 km = 30 km/h
• Speed attained to cover next 40 km = 20 km/h

We've been asked to calculate the average speed.

In order to calculate the average speed, firstly we need to calculate total distance and total time taken.

As the train is travelling on the track which has the length of 80 km, so total distance covered is 80 km.

⇒ Total distance covered = 80 km

Now, we have to find total time taken. Total time taken will be the sum of the time taken to cover first 40 km and time taken to cover next 40 km.

In first 40 km,

• Distance = 40 km
• Speed = 30 km/h

In next 40 km,

• Distance = 40 km
• Speed = 20 km/h

Basically, time can be written as distance ÷ speed. So,

→ Total time = Time taken to cover first 40 km + Time taken to cover next 40 km

→ Total time = (40/30 + 40/20) h

→ Total time = (4/3 + 2) h

→ Total time = (4 + 6)/3 h

⇒ Total time = 10/3 h

Now, as it is known to us that ❝ average speed is defined as the total distance covered divided by total time taken ❞ so,

➝ Average speed = Total Distance ÷ Total time

→ Average speed = 80 km ÷ 10/3 h

→ Average speed = (80 ÷ 10/3) km/h

→ Average speed = (80 × 3/10) km/h

→ Average speed = (8 × 3/1) km/h

⇒ Average speed = 24 km/h

∴ The average speed of the train is 24 km/h.

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