Two outposts M and N are 320 km apart. Train A leaves M for N at 40 km/h at 6:00 AM. Train B leaves N for M at 60 km/h at 8:00 AM. At what time will they cross? MCQ with Answer and Explanation
Two outposts M and N are 320 km apart. Train A leaves M for N at 40 km/h at 6:00 AM. Train B leaves N for M at 60 km/h at 8:00 AM. At what time will they cross?
A. 10:36 AM
B. 10:12 AM
C. 10:24 AM
D. 10:48 AM
Answer: Option C
Solution (By JKExamLibrary)
By 8:00 AM, Train A has run for 2 hours, covering 40 * 2 = 80 km. Remaining separation distance = 320 - 80 = 240 km. Relative speed = 40 + 60 = 100 km/h. Time after 8:00 AM = 240 / 100 = 2.4 hours = 2 hours 24 minutes. Meeting time = 8:00 AM + 2 hours 24 minutes = 10:24 AM.
A train passes a pedestrian standing on a platform in 6 seconds and passes the platform itself, which is 150 meters long, in 11 seconds. Find the speed of the train in km/h.
A man can walk a certain distance in 6 hours and ride back in 2 hours. If he rides both ways, he will save 2 hours. How much time will he take if he walks both ways?
Explanation:
Let W be walking time one way and R be riding time one way. W + R = 6 + 2 = 8 hours (total trip: walk one way, ride back). If he rides both ways, total time is 2R. He saves 2 hours, so 2R = 8 - 2 = 6 hours => R = 3 hours. From W + R = 8, W = 5 hours. Walking both ways takes 2W = 10 hours.
Explanation:
The train takes 25 - 10 = 15 seconds to cover the length of the platform. Speed of the train = 300 / 15 = 20 m/s. Length of the train = Speed * Time to cross the man = 20 * 10 = 150 meters.
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