A train 150 meters long is traveling at a speed of 45 km/h. How much time will it take to clear a platform 300 meters long? MCQ with Answer and Explanation

Explanation:
New speed = 7/9 of usual speed => New time = 9/7 of usual time. Difference = 2/7 of usual time = 12 minutes. 1/7 of usual time = 6 minutes => Usual time = 42 minutes.

Explanation:
Let original speed be s. 180 / (s - 5) - 180 / s = 1 => 180(5) = s(s - 5) => 900 = s(s - 5). Solving s^2 - 5s - 900 = 0 gives (s - 30)(s + 25) = 0. Since speed is positive, s = 30 km/h.

Explanation:
Speed of train = 72 * (5/18) = 20 m/s. Length of train = Speed * Time = 20 * 15 = 300 meters.