The harmonic mean is often used as a measure of central tendency for data sets consisting of

Question:

The harmonic mean is often used as a measure of central tendency for data sets consisting of rates of change, such as speeds. It is found by dividing the number of scores n by the sum of the reciprocals of all scores, expressed as

(No score can be zero.) For example, the harmonic mean of 2, 4, and 10 is

The harmonic mean is often used as a measure of

a. Four students drive from Toronto to Saint John (1440 km) at a speed of 60 km/h and return at a speed of 100 km/h. What is their average speed for the round trip? (The harmonic mean is used in averaging speeds.)
b. Jacques Villeneuve posted the average speeds (in kilometers per hour) shown below for his last 10 laps of practice, and in doing so qualified for the Canadian Grand Prix at Montreal. What was Villeneuve's average speed for these 10 laps?
192.8 191.6 197.5 198.2 199.1 197.6 196.5 197.5 193.5 190.0