A bullet train covers a fixed distance in 30 minutes at an average speed of…

First, calculate the original distance covered by the train. Since speed is 240 km/h and time is 30 minutes (or 0.5 hours), the distance equals speed multiplied by time: 240 × 0.5 = 120 km. Next, account for the increased distance due to track maintenance. The new route is 20% longer than the original, so multiply 120 km by 1.20 to get a new distance of 144 km. The train must still arrive in the same timeframe, which is 30 minutes or 0.5 hours. To find the required new average speed, divide the new distance by the time: 144 km ÷ 0.5 h = 288 km/h. This matches Option C. Options A and B are incorrect because they underestimate the necessary speed increase required to cover the extra 24 km within the fixed half-hour window. Option D is too high, exceeding what is mathematically required.