The Harmonic Mean Is Often Used as a Measure of Center

question 56

Multiple Choice

The harmonic mean is often used as a measure of center for data sets consisting of rates of change, such as speeds. It is found by dividing the number of values (n) by the sum of the reciprocals of all
Values, expressed as $$\frac { n } { \sum ( 1 / x ) }$$ Pierre drives to work (a distance of 50 miles) at a speed of 67 mph and returns home at a speed of 46 mph. What is his average speed for the round trip? Use the harmonic mean.

• A) 56.5 mph
• B) 56.2 mph
• C) 55.5 mph
• D) 54.5 mph

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