Question

By walking at $\frac{3}{4}$ the of his usual speed, a man reaches office 20 minutes later than usual. How much time he usually take?

• A. 30 min
• B. 60 min
• C. 70 min
• D. 50 min

Answer 1

The correct option is B

60 min

Take initial variables as Distance d, velocity v and time t. Modifying according to the current situation.
Equating distances (because distance is same for both the cases).
$\Rightarrow (0.75=\frac{3}{4})$
$\Rightarrow \left(0.75v\right)\times (t+20)=v\times t$
$\Rightarrow 3t+60=4t$
$\Rightarrow t=60min$