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2014-07-27T22:24:01+05:30

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Let V km/hr = speed of train
Let it travel for T hrs time.
480 km = V T            Eq 1
480 km =  (V-8) (T+3)  = VT -8T +3V -24      --- eq  2
equating both equations we get
     - 8 T + 3V -24 = 0
      - 8 (480/V) + 3 V - 24 = 0        - 3840 + 3 V^2 - 24 V  = 0
           V^2 - 8 V - 1280 = 0        V = (8 +- √ 64 + 4* 1280  ) / 2  = (8 +- 72 )/2
  V = 40 KMPH neglecting -ve vakue


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