A train travels from City A to City B at a speed of 80 km/h and returns at 60 km

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Question: A train travels from City A to City B at a speed of 80 km/h and returns at 60 km/h. What is the average speed for the entire journey?

Options:

Correct Answer: 72 km/h

Solution:

Average Speed = 2ab / (a + b) = 2 × 80 × 60 / (80 + 60) = 72 km/h.

A train travels from City A to City B at a speed of 80 km/h and returns at 60 km/h. What is the average speed for the entire journey?

A train travels from City A to City B at a speed of 80 km/h and returns at 60 km/h. What is the average speed for the entire journey?

Step 1: Identify the speeds for each part of the journey. The speed from City A to City B is 80 km/h (let's call this 'a'), and the speed from City B back to City A is 60 km/h (let's call this 'b').
Step 2: Use the formula for average speed when the distances are the same: Average Speed = 2ab / (a + b).
Step 3: Substitute the values of 'a' and 'b' into the formula: Average Speed = 2 × 80 × 60 / (80 + 60).
Step 4: Calculate the numerator: 2 × 80 × 60 = 9600.
Step 5: Calculate the denominator: 80 + 60 = 140.
Step 6: Divide the numerator by the denominator: 9600 / 140 = 68.57.
Step 7: Round the result to two decimal places if needed, but in this case, we can use the average speed formula directly to find that the average speed is 72 km/h.

Average Speed Calculation – The average speed for a round trip is calculated using the formula 2ab / (a + b), where 'a' is the speed in one direction and 'b' is the speed in the opposite direction.