# calculation of the harmonic mean

#### A PHP Error was encountered

Severity: Notice

Message: Undefined index: userid

Filename: views/question.php

Line Number: 212

Backtrace:

File: /home/mycocrkc/statisticsanswered.com/application/views/question.php

Line: 212

Function: _error_handler

File: /home/mycocrkc/statisticsanswered.com/application/controllers/Questions.php

Line: 416

Function: view

File: /home/mycocrkc/statisticsanswered.com/index.php

Line: 315

Function: require_once

## calculation of the harmonic mean

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. (No value can be zero.) The author drove 1163 miles to a conference in Orlando, Florida. For the trip to the conference, the author stopped overnight, and the mean speed from start to finish was 38 mi/h. For the return trip, the author stopped only for food and fuel, and the

mean speed from start to finish was 56 mi/h. Is the actual “average” speed for the round-trip the mean of 38 mi/h and 56 mi/h? Why or why not? What is the harmonic mean of 38 mi/h and 56 mi/h, and does this represent the true “average” speed?