Question
Due to fog, the speed of a train was reduced to
(2/3)rd of its original speed, resulting in a delay of 45 minutes. Find the usual time taken by the train to reach its destination.Solution
Let the distance travelled by the train be ‘d’ km, original speed be ‘s’ km/minute and usual time be ‘t’ minutes. ATQ; [d/{(2/3) × s}] = t + 45 Or, 3d = 2s × (t + 45) ………………… (1) Also, d = s × t ………………... (2) On combining equation (1) and (2), we have; 3st = 2s(t + 45) Or, 3st = 2st + 90s Or, st = 90s Or, t = 90 So, the usual time taken by the train to reach the destination is 90 minutes
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