Problem on Train

9.A train moves with a speed of 108 kmph. Its speed in metres per second is : A)28m/s B)25m/s C)29m/s D)30m/s Answer : Option D Explanation: 108 kmph =(108/(5/18))m/s = 30 m / s. 10.How many seconds will a 500 meter long train moving with a speed of 63 km/hr take to cross a man walking with a speed of 3 km/hr in the direction of the train ? A)30sec B)35sec C)32sec D)31sec Answer : Option A Explanation: Distance = 500 m Speed of the train relative to man= ( 63 - 3 ) km/hr = 60 km/hr = (60*5/18)m/s =50/3 m/s Time taken to pass the man = distance/speed = (500*50/3) sec = 30 sec 11.A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is: A)140m B)150m C)155m D)160m Answer : Option B Explanation: Let the length of the train be x metres and its speed be y m/sec. Then, (x/y)= 15 y =(x/15) => x+100/25=x/15 => 15(x + 100) = 25x => 15x + 1500 = 25x => 1500 = 10x => x = 150 m. 12.A Girl's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The Girl's speed against the current is : A)12km/hr B)14km/hr C)10km/hr D)16km/hr Answer : Option C Explanation: Gir's rate in still water = (15 - 2.5) km/hr = 12.5 km/hr. Gir's rate against the current = (12.5 - 2.5) = 10 km/hr.

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