Answer: Option D Explanation:Relative speed =(280/9) m/sec = (280/9*18/5) km/hr = 112 km/hr
Hence speed of the goods train =(112 - 50) = 62km/hr
Answer: Option C Explanation: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
Answer: Option B Explanation:Let the speed of the train be X km/hr
Speed of the train relative to man = (X+5) km/hr = (X+5) * 5/18 m/sec
100/(X+5)*5/18 = 6
30(X+5) = 1800 = X=55
Speed of the train is 55 Km/ph
Answer: Option A Explanation:Relative speed of the trains = (72-54 = 18 km/hr)
= (18*5/18) m/sec = 5m /sec
Time taken by the trains to cross each other
= Time taken to cover (100+120)m at 5 m/sec = (220/5)sec = 44 sec
Answer: Option B Explanation:Relative speed of the trains = (42+48) km/hr = 90km/hr
= (90*5/18) m/sec = 25 m/sec
time taken by the trains to pass each other
= Time taken to cover (137+163)m at 25 m/sec = (300/25) sec = 12 seconds.