A commercial van covers 1/3 of a route sector distance at 20 km/h, 1/3 at 40 km/h and the final 1/3 segment at 40 km/h. Find the mean average speed. MCQ with Answer and Explanation
A commercial van covers 1/3 of a route sector distance at 20 km/h, 1/3 at 40 km/h and the final 1/3 segment at 40 km/h. Find the mean average speed.
A. 30 km/h
B. 28 km/h
C. 32 km/h
D. 34 km/h
Answer: Option A
Solution (By JKSSB Mock Tests)
Let each third segment distance be 40 km. Total sector distance = 120 km. Total time = 40/20 + 40/40 + 40/40 = 2 + 1 + 1 = 4 hours. Average speed across route = 120 / 4 = 30 km/h.
Explanation:
Let total distance be 100 km. First segment = 30 km; Time = 30 / 15 = 2 hours. Second segment = 70 km; Time = 70 / 35 = 2 hours. Total distance = 100 km, Total time = 4 hours. Average speed = 100 / 4 = 25 km/h.
A train 270 meters long is moving at a speed of 120 km/h. In how much time will it cross a man coming from the opposite direction at a speed of 15 km/h?
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