1. Standard labor-hours allowed (SH) to ship 155,000 items to customers:
155,000 x 0.04 = 6200
Standard labor hours allowed to ship the above mentioned number of items is 6200
2. Standard variable overhead cost allowed: $3 x 6200 = $18600
3. Variable overhead spending variance : $(18600 - 17400) = $1200
4. (a) $ (18600/6000 - 3) 6000 = $600
b) $ (6200 - 6000) 3 = $600