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A man covers a distance of 180 km at a speed of 45 km/h, the next 150 km at a speed of 50 km/h and the next 120 km at a speed of x km/h. If…

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A man covers a distance of 180 km at a speed of 45 km/h, the next 150 km at a speed of 50 km/h and the next 120 km at a speed of x km/h. If his average speed for the whole journey is 47⁷⁄₁₉ km/h, then what is the value of x ?

Correct answer: A

Explanation

Total distance = 180 + 150 + 120 = 450 km. Average speed 47 7/19 = 900/19 km/h, so total time = 450 × 19/900 = 9.5 h. Time already used = 4 + 3 = 7 h, so 120/x = 2.5 and x = 48 km/h.

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