Two commuter trains 140 meters and 110 meters long are tracking in opposite directions at speeds of 40 km/h and 50 km/h respectively. In what time do they clear each other? MCQ with Answer and Explanation
Two commuter trains 140 meters and 110 meters long are tracking in opposite directions at speeds of 40 km/h and 50 km/h respectively. In what time do they clear each other?
A. 14 seconds
B. 8 seconds
C. 12 seconds
D. 10 seconds
Answer: Option D
Solution (By JKSSB Mock Tests)
Total distance = 140 + 110 = 250 meters. Relative speed in opposite directions = 40 + 50 = 90 km/h = 25 m/s. Time taken = 250 / 25 = 10 seconds.
Explanation:
New speed = 4/5 of usual speed => New time = 5/4 of usual time. Difference = 1/4 of usual time = 15 minutes. Usual time = 15 * 4 = 60 minutes.
A field clerk walking at 5 km/h handles a regular sector. If he steps up to run at 10 km/h, he takes 24 minutes less across the course stretch. Find the absolute distance profile.
A car driver leaves Bangalore at 8:30 AM and expects to reach a place 300 km away at 12:30 PM. At 10:30 AM he finds that he has covered only 40% of the distance. By how much must he increase the speed of the car to reach on scheduled time?
Explanation:
Total time available = 4 hours. At 10:30 AM (after 2 hours), distance covered = 40% of 300 = 120 km. Remaining distance = 180 km. Remaining time = 12:30 PM - 10:30 AM = 2 hours. Required speed = 180 / 2 = 90 km/h. Original speed = 120 / 2 = 60 km/h. Increase in speed = 90 - 60 = 30 km/h.
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