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InterviewSolution
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A planc left 30 minutes late than its scheduled timc and in order to reach the destination 15maway in time, it had to increase the speed by 250 kn/h from the usual speed. Find its usua stei |
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Answer» Let the usual time taken by the aeroplane = x km/hrDistance to the destination = 1500 km --------Speed = Distance / Time = (1500 / x) Hrs ------------Time taken by the aeroplane = (x - 1/2) Hrs Distance to the destination = 1500 kmSpeed = Distance / Time = 1500 / (x - 1/2) HrsIncreased speed = 100 km/hr[1500 / (x - 1/2)] - [1500 / x] = 100150((10/x-1/2)-10/x0=10015 /x -1/2- 15/x =130x -30x +15=2x^2-x15=2x^2-x2x^2-x-15=02x^2 - 6x+5x-15=02x(x-3)+5(x-3)2x+5=0 or x-3 =0x=-5/2 or x=3 Since, the time can not be negative,The usual time taken by the aeroplane = 3hrsand the usual speed = (1500 / 3) = 500km/hr |
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