Time and Distance – Find time from speed and distance (minutes and seconds): Rohit runs at a constant speed of 10 km/h. How many minutes will he take to cover a distance of 800 metres?

Difficulty: Easy

Correct Answer: 4 min 48 sec

Explanation:

Introduction / Context:We convert the given speed (km/h) to metres per second or keep it in km/h with hours-to-minutes conversions, then compute time = distance / speed and finally express it in minutes and seconds.

Given Data / Assumptions:

  • Speed = 10 km/h.
  • Distance = 800 m = 0.8 km.

Concept / Approach:Either convert to m/s or work in km and hours. Using m/s is usually quicker for second-accurate answers.

Step-by-Step Solution:10 km/h = 10000 m per 3600 s = 2.777... m/s.Time (s) = 800 / 2.777... ≈ 288 s.288 s = 4 min 48 s.

Verification / Alternative check:Working in km/h: time (h) = 0.8 / 10 = 0.08 h = 4.8 min = 4 min 48 s.

Why Other Options Are Wrong:4:36 and 4:40 are too small; 5:00 and 5:12 are too large for the given speed and distance.

Common Pitfalls:Rounding mid-calculation or mis-converting km/h to m/s (should be divide by 3.6 for m/s).

Final Answer:4 min 48 sec

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