2022 · Q7
A man walks at an average speed of 3 km/hr from his residence and reaches office 40 minutes early. If he walks at an average speed of 2 km/hr, he reaches 40 minutes late. what is the distance between his residence and office?
Elementary MathematicsTime, Speed and Distance
- A6 km
- B8 km
- C10 km
- D12 km
Explanation
Let the distance be d km and the scheduled travel time t hours. Then d/3 = t-2/3 and d/2 = t+2/3 (40 minutes = 2/3 hour). Subtracting eliminates t: d/2-d/3 = 4/3, so d/6 = 4/3 and d = 8 km. Hence the keyed option is B.