Question
A cyclist travelling at three-fourths of his usual speed
takes 12 minutes longer than his usual time to cover a certain distance. Calculate the usual time taken by him.Solution
ATQ,
Let the usual speed of the cyclist be '4s' km/h and the distance travelled be 'd' km.
Let the usual time taken by the cyclist to reach his destination be 't' hours.
ATQ;
(d/4s) = t
Or, d = 4ts ........ (I)
Now, if he travels at three-fourths of his speed:
(d/(3s)) = t + (12/60)
Using equation (I), we have;
(4ts/3s) = t + (1/5)
Or, 4t = 3t + (1/5)
Or, t = (1/5)
Thus, the usual time taken by the cyclist to reach his destination = (1/5) hours or 12 minutes.
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