When data consist of rates of change, such as speeds, the harmonic mean is an appropriate measure

Question:

When data consist of rates of change, such as speeds, the harmonic mean is an appropriate measure of central tendency. For n data values,
Harmonic mean = n/∑1/x, assuming no data value is 0
Suppose you drive 60 miles per hour for 100 miles, then 75 miles per hour for 100 miles. Use the harmonic mean to find your average speed.