Two trains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train is 120 meters, in what time will they cross each other traveling in opposite directions? MCQ with Answer and Explanation
Two trains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train is 120 meters, in what time will they cross each other traveling in opposite directions?
A. 15 seconds
B. 14 seconds
C. 12 seconds
D. 10 seconds
Answer: Option C
Solution (By JKSSB Mock Tests)
Speed of first train = 120 / 10 = 12 m/s. Speed of second train = 120 / 15 = 8 m/s. Total distance to cross each other = 120 + 120 = 240 meters. Relative speed in opposite directions = 12 + 8 = 20 m/s. Time = 240 / 20 = 12 seconds.
The speeds of two cars are in the ratio 4 : 3. If they cover the same distance, and the slower car takes 2 hours, how much time does the faster car take?
Explanation:
Ratio of speeds = 4:3, so ratio of times taken = 3:4. The slower car corresponds to 4 parts = 2 hours => 1 part = 0.5 hours. Time for the faster car = 3 parts = 3 * 0.5 = 1.5 hours.
A man covers 3/5 of his total journey by rail at 40 km/h and the remaining 2/5 by bus at 30 km/h. If the total distance is 150 km, what is the total time taken?
Explanation:
Distance by rail = 150 * (3/5) = 90 km. Time by rail = 90 / 40 = 2.25 hours. Distance by bus = 150 - 90 = 60 km. Time by bus = 60 / 30 = 2 hours. Total time = 2.25 + 2 = 4.25 hours.
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