A person takes 4 hours to cover 15 km at constant speed. At the same speed, how much time will be required to cover 63 km (express your answer in hours and minutes)?

Difficulty: Easy

Correct Answer: 16 h 48 min

Explanation:

Introduction / Context:Uniform speed implies distance is proportional to time. You can compute the speed first, or scale time by the distance ratio.

Given Data / Assumptions:

  • 15 km in 4 h → speed = 3.75 km/h.
  • Target distance = 63 km.

Concept / Approach:Time = distance / speed; or scale 4 h by the factor 63/15.

Step-by-Step Solution:

Speed v = 15 / 4 = 3.75 km/hTime t = 63 / 3.75 = 16.8 hoursConvert 0.8 h to minutes: 0.8 * 60 = 48 min → 16 h 48 min

Verification / Alternative check:Proportion method: 4 h * (63/15) = 4 * 4.2 = 16.8 h = 16 h 48 min.

Why Other Options Are Wrong:They correspond to other multipliers or rounding errors.

Common Pitfalls:Misconverting decimal hours to minutes; using 3.8 instead of 3.75 by mistake.

Final Answer:16 h 48 min

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