A boatman can row 4.5 km/h in still water. If the river flows at 1.5 km/h, it takes him 2 hours to row to a place and come back. How far is the place? MCQ with Answer and Explanation

Explanation:
Let the total distance be 120 km. First part = (2/3) * 120 = 80 km; Time = 80 / 40 = 2 hours. Second part = (1/4) * 120 = 30 km; Time = 30 / 30 = 1 hour. Remainder = 120 - 80 - 30 = 10 km; Time = 10 / 10 = 1 hour. Total time = 2 + 1 + 1 = 4 hours. Average speed = 120 / 4 = 32 km/h.

Explanation:
Time = 1 minute 40 seconds = 100 seconds. Speed = 5000 / 100 = 50 m/s. In km/h = 50 * (18/5) = 180 km/h.

Explanation:
Speed of train = 36 * (5/18) = 10 m/s. Length of train = Speed * Time to cross post = 10 * 6 = 60 meters. Total distance to cross platform = Speed * Time = 10 * 12 = 120 meters. Platform length = 120 - 60 = 60 meters.