I am confused on the moving average unit cost.

Company inventory:

Date	Explanation	Units	Unit cost	Total Cost
March 1	Inventory	200	$2	$400
March 12	Purchase	600	$3	$1800
March 23	Purchase	230	$4	$920
March 30	Inventory	60

Sales happen on the 15th of 480 units at $6 and again on the 27th of 120 units for $6.

I'm having trouble calculating for each of the dates with the sales in between: (to the 3rd decimal) March 1 March 12 March 15 March 23 March 27