A boat can row 10 km/h in still water and the river current marks 4 km/h. Find the time required to complete 42 km downstream. MCQ with Answer and Explanation

Explanation:
Time = 2 minutes + 30 seconds = 150 seconds. Speed = 750 / 150 = 5 m/s. Converting to km/h: 5 * (18/5) = 18 km/h.

Explanation:
Let the speeds be 7x and 9x. Length of first train = 7x * 4 = 28x. Length of second train = 9x * 4 = 36x. Total distance to cross each other = 28x + 36x = 64x. Relative speed in opposite directions = 7x + 9x = 16x. Time taken = 64x / 16x = 4 seconds.

Explanation:
Stoppage time per hour = (90 - 75) / 90 = 15 / 90 = 1/6 hour. In minutes = (1/6) * 60 = 10 minutes.