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. MCQ with Answer and 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.