PMP Exam – Communication Formula

Posted on February 3, 2009 by

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There are a number of formulas to memorize before taking the PMP Exam. The good news is that once you know the formulas, those questions should be particularly easy to answer correctly as there is a definite right answer. Here we’ll review the communication formula, which is used to calculate the number of possible paths of two-way communication among a group of people. The formula is (N * (N-1))/2 where N is the number of people in the group. So if you have 4 people in your group, the number of communication paths is (4*3)/2 which is 12/2 which is 6.

Let’s use an example—say the four people in your group are Annie, Barney, Cathy, and Dannie. Annie could talk directly to any of the other three—Barney, Cathy, and Dannie—which makes 3 paths of communication. We’ve already accounted for Barney and Annie talking to each other, but Barney could also talk directly to Cathy or Dannie, which adds 2 more communication paths. Lastly, Cathy and Dannie could talk directly to each other (we’ve already accounted for them talking to Annie and Barney), so that adds 1 more communication path. So 3 paths, plus 2 paths, plus 1 more path equals 6 paths, which is exactly what we quickly calculated using the communication formula.

If you’d like some practice with this formula, try answering the following:

1. There are 10 people on the project management team. How many communication paths are there?

2. There were 8 people on the team, but 2 people left. How many communication paths are there now?

3. There were 5 people on the team, but the team has now doubled in size. How many communication paths have been added?