Question 111

Walking at $$\ \frac{3}{4}\ $$of his usual speed, a man reaches his office 20 minutes late. Then his usual time for walking to his office is:

Solution

Let usual speed = $$4$$ m/min and usual time taken = $$t$$ min

New speed = $$\frac{3}{4}\times4=3$$ m/min and new time taken = $$(t+20)$$ minutes

Also, speed is inversely proportional to time.

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

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

=> $$4t-3t=t=60$$

$$\therefore$$ Usual time taken to reach office = 60 minutes = 1 hour

=> Ans - (A)

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