Jake Co. recorded the following data pertaining to raw material X during January 2012:

Received Cost Issued On Hand

1/1/12 inventory $8.00 $3200

1/11/12 inventory $1,600 $1,600

1/22/12 purchase $4,800 $9.60 $6400

What is the weighted-average cost per unit of material on hand at January 31, 2012, assuming that Jake Co. uses the perpetual inventory procedure.