A person walks from his house to his office at a speed of 4 km/h and reaches 10 minutes late. If he walks at 5 km/h, he reaches 5 minutes early. Find the distance between his house and office.
An express train covers a distance of 450 km in 5 hours. If a slower local train runs at half the speed of the express train, how much time will the local train take to cover 360 km?
A cross-country runner covers the sides of an equilateral triangular course at speeds of 8 km/h, 12 km/h and 24 km/h respectively. Find his average speed for the whole round.
Explanation:
Let each side of the triangular course be 24 km. Total perimeter = 3 * 24 = 72 km. Total time taken = 24/8 + 24/12 + 24/24 = 3 + 2 + 1 = 6 hours. Average speed = 72 / 6 = 12 km/h.
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