A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.
Correct answer: C. 224 km
- A. 121 km
- B. 242 km
- C. 224 km
- D. 112 km
Explanation
Let each half of the journey be x km. The total time is x/21 hours + x/24 hours = 10 hours, so x(45/504) = 10 and x = 112 km; the complete journey is 2 x 112 km = 224 km. The likely mistake is choosing 242 km by using an incorrect average speed instead of adding the two half-journey times.
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