Question

On a journey across Kolkata, a taxi averages 40 kmph for 60% of distance, 30 kmph for 20% of the distance, and 10 kmph for the remainder. The average speed of the whole journey is

• A. 25 kmph
• B. 26 kmph
• C. 24 kmph
• D. 30 kmph

Answer 1

The Correct Option is C

To determine the average speed of the entire journey, we use the formula for average speed: Average Speed = Total Distance / Total Time.

Let the total distance be d km.

For the first segment: 60% of distance = 0.6d, speed = 40 kmph.
Time taken = Distance / Speed = 0.6d / 40 hours.

For the second segment: 20% of distance = 0.2d, speed = 30 kmph.
Time taken = 0.2d / 30 hours.

For the remaining segment: 20% of distance = 0.2d, speed = 10 kmph.
Time taken = 0.2d / 10 hours.

Total time = 0.6d / 40 + 0.2d / 30 + 0.2d / 10

Simplifying,
Total time = 0.015d + 0.00667d + 0.02d = 0.04167d hours

Average speed = d / 0.04167d = 24 kmph

Thus, the average speed of the whole journey is 24 kmph.