If I walk at 3 mph (miles per hour), I miss the train by 2 minutes. If however, I walk at 4 mph, I reach the station 2 minutes before arrival of the train. How far do I walk to reach the station?
- 1 mile
The Usual Method
Let the distance between home and station be ‘4’ miles. Hence, time taken to cover d miles at 3 mph, hours.
Similarly, time taken at 4 mph, hours
Estimated Time to arrive at the answer = 45 seconds.
To cover 1 mile @ 3 mph, it takes 20 minutes
To cover 1 mile @ 4 mph, it takes 15 minutes
Hence, time gap = 20 – 15 = 5 minutes
Thus for a distance of 1 mile, time gap = 5 minutes
Hence, a time gap of 4 minutes (2 + 2), distance is correspondingly mile.
Estimated Time to arrive at the answer = 10 seconds.