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    Question

    A flight has to travel between 2 cities A and B, 2000 km

    apart. The flight was slowed down due to bad weather. Its average speed for the trip reduced by 200 km/hr and the time of flight increased by 30 min. The duration of the flight with original speed is:
    A 2 hrs Correct Answer Incorrect Answer
    B 2.25 hrs Correct Answer Incorrect Answer
    C 2.6 hrs Correct Answer Incorrect Answer
    D 2.75 hrs Correct Answer Incorrect Answer

    Solution

    According to question, => (2000/t) – (2000/(t+1/2)) = 200 => (10/t) – (10/(t+1/2)) = 1 => (1/t) – (1/(t+1/2)) = 1/10 => 10 = 2t2 + t => 2t2 + t – 10 = 0 => 2t2 + 5t – 4t – 10 = 0 => t(2t + 5) – 2(2t + 5) = 0 => (2t + 5) (t – 2) = 0 => t = -5/2, 2 (time is not possible in negative) Required time = 2 hours

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