title: Different results returned between SUM()/total rows and AVG() in sql server
body: <p>I have a table #time_per_bike with 6549 rows (no duplicates present. Even the bikeid column has unique IDs). Please see the sample -</p>
  
  <p><img src="https://i.stack.imgur.com/5AovM.jpg" alt="Sample Data"></p>
  
  <p>Can anybody tell me why am I getting different results between the two queries (since I believe they do same operation. Please correct me if I am wrong)? </p>
  
  <pre><code>select SUM(AVG_WAIT_TIME)/6549 from #time_per_bike
  -- Returns 69499
  
  select AVG(AVG_WAIT_TIME) from #time_per_bike
  -- Returns 69520
  </code></pre>