title: Convert interval to number in postgresql
body: <p>I have created a query which sums up the interval for respective date-time,</p>
  
  <pre><code>select sum(ts_polling) / count(ts_polling) as Average_Queue_Wait_Time ,  cast(time_start AS Date)
    from callcent_queuecalls group by cast(time_start AS date) order by time_start DESC;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/NI6BX.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NI6BX.jpg" alt="enter image description here"></a></p>
  
  <p>Is there a way to convert Average_Queue_Wait_Time from interval data type to number ?</p>