A train 300 meters long requires exactly 25 seconds to pass a railway worker running at 6 km/h in the opposite direction. Find the speed of the train. MCQ with Answer and Explanation
A train 300 meters long requires exactly 25 seconds to pass a railway worker running at 6 km/h in the opposite direction. Find the speed of the train.
A. 34.2 km/h
B. 43.2 km/h
C. 40.0 km/h
D. 37.2 km/h
Answer: Option D
Solution (By JKExamLibrary)
Relative speed = 300 / 25 = 12 m/s = 12 * (18/5) = 43.2 km/h. Since they move in opposite directions, Relative Speed = Speed of train + Speed of worker => 43.2 = Speed of train + 6 => Speed of train = 37.2 km/h.
Explanation:
New speed = 3/5 of normal speed => New time = 5/3 of normal time. Difference = 2/3 of normal time = 16 minutes. Normal baseline time = (16 * 3) / 2 = 24 minutes.
The speed of a boat in still water is 14 km/h and the speed of the current is 4 km/h. How much time will the boat take to cover a distance of 72 km downstream?
Explanation:
Downstream speed = Speed in still water + Speed of current = 14 + 4 = 18 km/h. Time taken = Distance / Downstream speed = 72 / 18 = 4 hours.
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