A train 180 meters long running at 54 km/h passes a stationary point tracking observer. Find the time parameter required to cross. MCQ with Answer and Explanation

Explanation:
Total distance = 120 + 180 + 100 = 400 km. Total time = (120/40) + (180/60) + (100/50) = 3 + 3 + 2 = 8 hours. Average speed = 400 / 8 = 50 km/h.

Explanation:
Upstream speed = 16 / 4 = 4 km/h. Upstream Speed = Speed in still water - Current speed => 4 = Speed in still water - 1 => Speed in still water = 5 km/h.

Explanation:
Let original speed be s. 360/s - 360/(s+15) = 2 => 180/s - 180/(s+15) = 1 => 180(15) = s(s+15) => 2700 = s(s+15). Solving s^2 + 15s - 2700 = 0 gives (s - 45)(s + 60) = 0. Since speed is positive, s = 45 km/h.