Question 119

By walking at 3/4 of his usual speed, a man reaches his office 20 minutes later than usual. His usual time is

Solution

Let the original speed of man be $$4x$$ and he reaches his office in $$t$$ min.

New speed = $$3x$$ and new time taken = $$(t + 20)$$ min

$$\because speed \propto \frac{1}{time}$$

=> $$\frac{4x}{3x} = \frac{t + 20}{t}$$

=> $$4t = 3t + 60$$

=> $$t = 60$$ min

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