As part of his journey, a person travels 120 km at 80 km/h, the next 100 km at 40 km/h, and comes back to the starting point at 75 km/h. The average speed of the person throughout the journey (approximately) is:
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Combined Graduate Level Examination Tier I 2023
63.46 km/h
Correct Answer58.74 km/h
Incorrect Answer68.15 km/h
Incorrect Answer49.58 km/h
Incorrect AnswerExplanation:
- To find the average speed, we need total distance divided by total time taken.
- The first part: 120 km at 80 km/h ? time = 120/80 = 1.5 hours.
- The second part: 100 km at 40 km/h ? time = 100/40 = 2.5 hours.
- The return: Total distance so far is 220 km, so return is 220 km at 75 km/h ? time = 220/75 ˜ 2.93 hours.
- Total distance travelled = 120 + 100 + 220 = 440 km.
- Total time taken = 1.5 + 2.5 + 2.93 ˜ 6.93 hours.
- Average speed = 440 / 6.93 ˜ 63.46 km/h.
- Option 1 (63.46 km/h) is correct.
- Other options do not match this calculation.
Option 1: 63.46 km/h is the correct answer.
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By: Parvesh Mehta