21.  A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is?


50 m
150 m
200 m
Data inadequate


Answer

 Option

Let the length of the train be x meters and its speed be y m/sec They x/y =15 Y=x/15 x+100/25 = x/15 x=150 m

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22.  A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train?


120 meters
180 meters
150 meters
None of these


Answer

 Option

Speed = (60*5/18) m/sec = (50/3) m/sec. Length of the train = (speed * time) = (50/3*9) m = 150 m.

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23.  A train running at 54 km/ph takes 20 seconds to pass a platform.Next it takes 12 seconds to pass a man walking at 6km/ph in the same direction in which the train is going.Find the length of the train and the length of the platform?


135 m
142 m
140 m
138 m


Answer

 Option

Let the length of the train be X meters and length of platform be Y meters. Speed of the train relative to man = (54-6) km/ph =48 km/ph = (48*5/18)m/sec = 40/3 m/sec In passing a man the train covers its own length with relative speed. Length of train =(relative speed * time) = (40/3*12)m =160m Also speed of the train =(54*5/18)m/sec = 15 m/sec Hence x+y/15 =20 x+y = 300 y= (300 -160) m = 140 m

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24.  A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds.If the speed of the train is 54 km/hr,what is the length of the platform?


120 m
240 m
300 m
None of these


Answer

 Option

Speed = (54*5/18) m/sec = 15 m/sec. Length of the train =(15*20) m = 300m Let the length of the platform be X meters Then X+300/36 = 15<=> X+300 = 540 <=> X= 240m

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25.  A train of length 150 m takes 40.5 sec to cross a tunnel of length 300 m.What is the speed of the train in km/hr?


13.33
26.67
40
66.67


Answer

 Option

Speed =(150+300/40.5) A meter per second = (450/40.5*18/5) km/hr = 40 km/hr

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