Headlands Industries uses a periodic inventory system. Its records show the following for the month of May, in which 77 units were sold Date May 1 15 24 Explanation Inventory Purchase Purchase Total Units 31 23 37 91 Unit Cost $10 11 12 Total Cost $310 253 444 $1.007 (a) Calculate the wehted average unit cost Mound answer to decimal placeses $125) Weighted average unit cost