mackie co. manufactures hunting clothing. the standard variable costs to produce one batch of the big mac vests are as follows: direct material average cost is $6 per yard; average yards per batch is 20; direct labor average rate per hour is $12; average hours per batch is 4; variable overhead average rate per hour is $8; average hours per batch is 4. the standard monthly fixed costs are as follows: manufacturing overhead is $3,200; selling and administrative costs are $1,900. mackie co. produces 100 batches per month. (ten vests are produced in each batch.) what is the manufacturing cost per vest?