A boatman rows 15 km downstream in 3 hours and 12 km upstream in 4 hours. What is the speed of the boat in still water? MCQ with Answer and Explanation
A person runs along the sides of an equilateral triangular field at speeds of 10 km/h, 15 km/h and 30 km/h respectively. Find his average speed for the entire perimeter.
Explanation:
Let each side of the triangular field be 30 km (LCM of 10, 15, 30). Total distance = 3 * 30 = 90 km. Total time taken = 30/10 + 30/15 + 30/30 = 3 + 2 + 1 = 6 hours. Average speed = 90 / 6 = 15 km/h.
In a 500-meter dash trial heat, runner A clocks across the tape in 50 seconds, while runner B marks a finish layout in 55 seconds. By what distance does runner A beat runner B?
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