title: Calculate Average Across Multiple Pairs/Permutations
body: <p>Not sure how to use <code>AVERAGEIFS</code> or a combination of <code>SUMIFS</code> and <code>COUNTIFS</code> to efficiently solve this, or some other function.</p>
  
  <p>Basically, assume I have the following dataset of trip times between certain points</p>
  
  <pre><code>Start   End   Trip Time(Minutes)
  
  A       B     12
  A       B     8
  B       A     9
  B       A     2
  A       C     15
  C       A     5
  C       B     11
  C       B     9
  B       C     7
  A       B     16
  A       D     18
  D       C     21
  E       A     11
  X       Y     19
  </code></pre>
  
  <p>There could be n number of points in the dataset, but assume we are only interested in the average trip time of all trip pairs between 4 cities (A,B,C,D). i.e. AB, BA, AC, CA, BD, DB, etc. but not AA, BB, CC, DD.</p>
  
  <p>How can I go about averaging the trip time between all these permutations? Much help would be appreciated..thank you!</p>