A train 180 meters long passes a pole in 9 seconds. What is the speed of the train in km/h? MCQ with Answer and Explanation

Explanation:
Let original speed be s. 240 / (s - 10) - 240 / s = 2 => 120 / (s - 10) - 120 / s = 1 => 1200 = s(s - 10). Solving s^2 - 10s - 1200 = 0 gives (s - 40)(s + 30) = 0. Since speed is positive, s = 40 km/h.

Explanation:
New speed = 4/5 of usual speed => New time = 5/4 of usual time. Difference = 1/4 of usual time = 15 minutes. Usual time = 15 * 4 = 60 minutes.

Explanation:
Distance = 6.6 km = 6600 meters. Time taken = 6600 / 330 = 20 seconds.