A person travels equal distance with speeds of 3 km/hr, 4 km/hr and 5 km/hr and taken a total time of 47 minutes. The total distance (in km) is :

Answer: Option B

Let the total distance be 3x km
Then,
$$\begin{array}{rl}& \iff \frac{x}{3}+\frac{x}{4}+\frac{x}{5}=\frac{47}{60}\\ & \iff \frac{47x}{60}=\frac{47}{60}\\ & \iff x=1\end{array}$$
∴ Total distance = (3 × 1) km = 3 km