A sedan tracks from location M to N at 50 km/h and manages the return tract to M at 70 km/h. What is the average speed recorded across the round journey? MCQ with Answer and Explanation
A sedan tracks from location M to N at 50 km/h and manages the return tract to M at 70 km/h. What is the average speed recorded across the round journey?
A. 58.33 km/h
B. 56.50 km/h
C. 61.25 km/h
D. 60.00 km/h
Answer: Option A
Solution (By JKSSB Mock Tests)
Average Speed across course = 2xy / (x + y) = (2 * 50 * 70) / (50 + 70) = 7000 / 120 = 58.33 km/h.
A train passes a standing person on a platform in 8 seconds and crosses the platform itself, which is 240 meters long, in 20 seconds. Find the length of the train.
Explanation:
Time taken to cross the platform distance alone = 20 - 8 = 12 seconds. Speed of the train = 240 / 12 = 20 m/s. Length of the train = Speed * Time to pass the person = 20 * 8 = 160 meters.
Explanation:
Let total distance be 100 km. First part = 40 km; Time = 40 / 20 = 2 hours. Second part = 60 km; Time = 60 / 30 = 2 hours. Total distance = 100 km, Total time = 4 hours. Average speed = 100 / 4 = 25 km/h.
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