A train 125 m long passes a man, running at 5 kmph in the same direction in which the train is going, in 10 seconds. The speed of the train is: A.35 km/hr B.50 km/hr C.48 km/hr D.55 km/hr E.None of these

1 Answer

Answer :

Answer – B (50 km/hr)

Explanation – Let speed be S

Relative speed = total lengths/time [ in this case man length is neglible

compare to train so neglected] (S – 5) x 5/18 = 125 /10

S- 5 = (125/10)x(18/5)

S-5 = 45

S=50 km/hr

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Last Answer : ANSWER : C Explanation:  Length of the train = 110 m  Speed of the train = 30 km/hr  Speed of the boy = 3.5 km/hr  Speed of the train relative to man = (30 + 3.5) km/hr  = 33.5 km/hr  Convert km/ ... cover 110 m at 9.30 m/s  = 110 / 9.30  = 11.8 seconds  = 12 sec(approx.).

Description : A goods train overtakes two boys who are walking in the same direction in which the train is going, at the rate of 4 kmph and 8 kmph and passes them completely in 18 and 20seconds respectively. The length of the goods train is : A) 50m B) 200m C) 160m D)80 m 

Last Answer : ANSWER:B  Explanation:  Let the length of the goods train be x km and its speed be y km/hr.  Then, speed relative to first boy = (y-4) km/hr.  Speed relative to second boy = (y-8) km/hr.  x/y-4 ... )- 72 / 3600  = 720/3600 = 0.2*1000 = 200 m  Therefore the length of the goods train is 200m

Description : The Mumbai express 500m long passes a man running at 20km/hr in the same direction in which the express is going in 40sec. The speed of the express is. A) 50km/hr B) 45km/hr C) 25km/hr D) 65km/hr

Last Answer : ANSWER : D Explanation:  Length of the train = 500m  Speed of the expess relative to man = (500 / 40)m/s  = 25/2 m/s  Convert m/s into km/hr  25 / 2 m/s = 25 / 2 * 18 / 5 = 45 km/hr  Let the ... x -20)km/hr  Therefore x - 20 = 45  x = 45 + 20  = 65km/hr  Speed of the express = 65 km/hr.