And amount of gross margin assuming the FIFO cost flow method used ?

The inventory records for Radford Company reflected the following Beginning inventory on May 1 First purchase on May 7 second purchase on May 17 Third purchase on May 23 Sales on May 31 1,800 units @ $5.20 1,900 units @ $5.40 2,100 units @ $5.50 1,700 units @ $5.60 5,700 units @ $7.10 What is the weighted average cost per unit for May