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29 Jan 2021, 09:45
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
65%
(hard)
Question Stats:
60% (02:52) correct
40%
(02:45)
wrong
based on 145
sessions
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A man is standing on a railway bridge which is 70 m long. The man finds that a train crosses the bridge in \(5 \frac{1}{2}\) seconds but the man himself in 2 sec. What is the length of the train and its speed?
(A) 40 m, 72 km/hr.
(B) 50 m, 65 km/hr.
(C) 100 m, 50 km/hr.
(D) 110 m, 50 km/hr.
(E) 120 m, 50 km/hr.
(A) 40 m, 72 km/hr.
(B) 50 m, 65 km/hr.
(C) 100 m, 50 km/hr.
(D) 110 m, 50 km/hr.
(E) 120 m, 50 km/hr.
29 Jan 2021, 10:01
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Let the length of the train = x and its speed = y m/s
Time = Distance / Speed
When crossing the bridge, 5.5 = (70 + x) / y ... (1)
When crossing the man, 2 = x / y. Therefore x = 2y ... (2)
Putting (2) in (1), we get 5.5 = (70 + 2y) / y
5.5y = 70 + 2y
3.5 y = 70
y = 20 m/s = 20 * (18/5) = 72 km / hr
x = 2y = 2 * 20 = 40 m
Option A
Arun Kumar
Time = Distance / Speed
When crossing the bridge, 5.5 = (70 + x) / y ... (1)
When crossing the man, 2 = x / y. Therefore x = 2y ... (2)
Putting (2) in (1), we get 5.5 = (70 + 2y) / y
5.5y = 70 + 2y
3.5 y = 70
y = 20 m/s = 20 * (18/5) = 72 km / hr
x = 2y = 2 * 20 = 40 m
Option A
Arun Kumar
General Discussion
29 Jan 2021, 11:38
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An easy approach to solve this question in less than 30 sec.
Ans A
Ans A
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