Question 457371
Your first mile would take 1 hour at 1 mph.  Your second mile would take 1/2 hour.
Your third mile takes 1/3 hour, etc., etc.. Following this pattern is known as the harmonic series and the sum of the first 100 terms is 5.187.  So you've traveled 100 miles over 5.187 hours, so your average speed was 100/5.187 or 19.28 mph..