Practicing Success
A train crosses two bridges 370 m and 480 m long in 51 and 62 seconds respectively. Find the speed of the train.
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24 kmph 36 kmph 45 kmph 64 kmph |
36 kmph |
Speed = \(\frac{ Distance}{ Time}\) Let the length of the train be x So, according to the question: Speed = \(\frac{ \text{x + 370}}{51}\) m/s ---------1st equation Speed = \(\frac{\text{x + 480}}{62}\) m/s ----------2nd equation From 1st and 2nd equation: \(\frac{ \text{x + 370}}{51}\) = \(\frac{\text{x + 480}}{62}\) 62x + 22940 = 51x + 24480 11x = 1540 x = \(\frac{ 1540}{11 }\) x = 140 Length of the train = 140 m Speed of the train = \(\frac{ \text{140 + 370}}{51}\) Speed of the train = \(\frac{ \text{510}}{51}\) Speed of the train = 10 m/s Speed of train in km/hr = 10 x \(\frac{ 18}{5 }\) km/hr Speed of train in km/hr = 36 km/hr |