Multiple choice

A boy rides his bicycle 10 km at an average speed of 12 km per hr and again travels 12 km at an average speed of 10 km per hr. His average speed for the entire trip is approximately :

  1. $10.4 km/hr$
  2. $10.8 km/hr$
  3. $11.0 km/hr$
  4. $12.2 km/hr$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed = Total distance / Total time = (10+12) / (10/12 + 12/10) = 22 / (0.833 + 1.2) = 22 / 2.033 ≈ 10.82 km/hr, closest to 10.8 km/hr. Do NOT use simple average (11 km/hr) which ignores time weighting.

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