A bus moving at 42 km/h covers a distance in 8 hours. At what speed must it travel to cover the same distance in 6 hours? MCQ with Answer and Explanation

Explanation:
Let each side of square be 2400 km (LCM of 200, 400, 600, 800). Total distance = 4 * 2400 = 9600 km. Total time = 2400/200 + 2400/400 + 2400/600 + 2400/800 = 12 + 6 + 4 + 3 = 25 hours. Average speed = 9600 / 25 = 384 km/h.

Explanation:
Let original speed be s. 300/s - 300/(s+10) = 1 => 3000 = s(s+10). Solving s^2 + 10s - 3000 = 0 yields (s-50)(s+60) = 0. Speed = 50 km/h.

Explanation:
Relative speed = 100 / 6 = 50/3 m/s = (50/3) * (18/5) = 60 km/h. Since the train passes him from behind (same direction), Relative Speed = Speed of train - Speed of man => 60 = Speed of train - 5 => Speed of train = 65 km/h.