Multiple choice

A car covers four consecutive stretches of 4 km each at the speeds of 10 kmph, 20 kmph, 30 kmph and 60 kmph. Its average speed for the journey is

  1. 10 kmph

  2. 20 kmph

  3. 30 kmph

  4. 25 kmph
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed = Total distance / Total time. Total distance = 4 * 4 = 16 km. Total time = 4/10 + 4/20 + 4/30 + 4/60 = (24+12+8+4)/60 = 48/60 = 0.8 hours. Average speed = 16 / 0.8 = 20 kmph.

AI explanation

Using the average speed formula for equal distances, Average Speed = Total Distance divided by Total Time, the total distance is 16 km. The total time is (4/10) + (4/20) + (4/30) + (4/60) hours, which equals 4/5 hours. Dividing 16 km by 4/5 hours gives an average speed of 20 kmph. The result is 20 kmph.

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