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Time for the secondary wave from the source to the station is minutes, where d is the distance from the source to the station.
Time for the primary wave from the source to the station is minutes, where d is the same distance from the source to the station.
Your equation is
- = 5.07 minutes (the "time difference" equation).
From the equation
d = = (at this point I use Excel spreadsheet in my computer) = 3386 kilometers.
Answer. The distance from the source to the station is 3386 kilometers.
Solved.