A man is walking at a speed of 12 km/hrs. After every kilometer he takes rest for 5 minutes. How much time will he take to cover a distance of 12 km?

1. A

   1 hour 55 minutes

2. B

   1 hour 60 minutes

3. C

   1 hour 65 minutes

4. D

   3 hours 55 minutes

Appeared in: DSSSB 6 September 2024

Explanation

• The problem requires calculating total journey time by summing up the continuous travel time and the cumulative rest time.
• First, calculate the time taken to travel without any stops: Time = Distance / Speed = 12 km / 12 km/hr = 1 hour.
• Next, determine the number of rests. Since a rest is taken after each kilometer, for a 12 km journey, rests occur at the 1 km, 2 km, ..., up to the 11 km mark. No rest is taken at the 12 km mark as the journey is complete. This gives a total of 11 rests.
• Calculate the total rest time: 11 rests × 5 minutes/rest = 55 minutes.
• Finally, add the walking time and the rest time: 1 hour + 55 minutes = 1 hour 55 minutes.

Why Other Options Were Wrong

• Option B: This answer incorrectly calculates the total rest time as 60 minutes, which implies 12 rests (12 rests × 5 minutes = 60 minutes).
• Option C: This answer incorrectly calculates the total rest time as 65 minutes, which implies 13 rests (13 rests × 5 minutes = 65 minutes).
• Option D: This answer grossly overestimates the total time. The walking time is only 1 hour, so an additional 2 hours and 55 minutes of rest is mathematically incorrect.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of total time taken for a journey with periodic rests as background academic context rather than a clinical decision trigger.
• While this is a general aptitude question, the underlying skill of meticulous, step-by-step calculation is critical in nursing.
• Nurses use similar logical reasoning for calculating medication dosages, IV drip rates, and patient intake/output over a specific period, where missing a step or miscalculating can have significant patient safety consequences.
• What if? If the man took rest for 10 minutes instead of 5, the total rest time would be 11 rests × 10 minutes = 110 minutes (1 hour 50 minutes). The total time would then be 1 hour (walking) + 1 hour 50 minutes (rest) = 2 hours 50 minutes.

How to Approach the Question

• First, identify all the numerical data provided: Speed (12 km/hr), Total Distance (12 km), Rest Duration (5 minutes), and Rest Interval (every 1 km).
• Calculate the base travel time as if there were no stops. Use the formula: Time = Distance / Speed.
• Determine the number of rest stops. The key is to understand that the rest is taken after completing a segment, not at the very end of the total journey. The number of stops will be one less than the number of segments.
• Calculate the total time spent resting by multiplying the number of stops by the duration of each rest.
• Sum the base travel time and the total rest time to get the final answer.
• Convert the final time in minutes to the 'hours and minutes' format required by the options.

Concept Tested & Keywords

• Concept Tested: Calculation of total time taken for a journey with periodic rests.
• Stem keywords: speed, 12 km/hrs, rest, 5 minutes, distance, 12 km
• Lead-in keywords: How much time

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Q94wvnRpYvbfeiols-FyYo

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