Multiple choice

Water flows into a tank 180 m × 140 m through a rectangular pipe of 1.2 m × 0.75 m at a rate of 15 km/h. In what time will the water rise by 4 m?

  1. 7 hours 28 minutes

  2. 6 hours 42 minutes

  3. 8 hours 12 minutes

  4. 5 hours 46 minutes
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A Correct answer
Explanation

Volume of water needed = 180 * 140 * 4 = 100,800 cubic meters. Flow rate of pipe = 1.2 * 0.75 * 15,000 = 13,500 cubic meters per hour. Time = 100,800 / 13,500 = 7.4666 hours, which is 7 hours and 28 minutes.

AI explanation

The required volume of water is found by multiplying the base area by the target height: 180 m * 140 m * 4 m = 100800 cubic meters. The volume of water supplied by the pipe per hour is its cross-sectional area multiplied by the flow rate: 1.2 m * 0.75 m * 15000 m/h = 13500 cubic meters per hour. Dividing the total volume needed by the hourly rate gives 100800 / 13500 = 7.4666 hours. Converting this to hours and minutes gives 7 hours and 28 minutes, which is the time needed for the water to rise by 4 meters.

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