Mohammad,
I can't answer your question directly, but I do want to point out a common misconception.
You state that Total calls entered the Queue = calls Answered + calls Abandoned, but for any given time period that is not necessarily the case. It is entirely possible (indeed a common cause of confusion) for more calls to be answered in a time period than entered the queue! Or to have more calls enter than the total of Answered and Abandoned.
Let us say that at 7:30, we have 3 calls still waiting from the previous period. Between 7:30 and 8:00, 10 new calls arrive, 5 calls get answered and 6 calls abandon. At 8:00, there will be 2 calls still waiting in the queue. In this example, only 10 arrived, but the total of abandon and answer is 11!
So, your formula should be Total calls entered the queue = Call Answered + Calls Abandoned + Calls remaining in queue at the end of the period - Calls already in the queue at the start of the period. (Or re-arrange if necessary.)
As I said, this is a common point of confusion for folks trying to read the reports and live stats.
I hope this helps.