Answer:
The following multiple choices are missing:
$8.10 per machine-hour
$2.10 per machine-hour
$3.90 per machine-hour
$6.00 per machine-hour
The predetermined overhead rate is $6
Explanation:
The predetermined overhead rate is the sum of the fixed manufacturing overhead cost per machine hour and variable manufacturing overhead per machine hour
fixed manufacturing overhead cost per machine=total fixed manufacturing overhead/total machine hours
fixed manufacturing overhead=$312,000
total machine hours is 80,000 hours
fixed manufacturing overhead cost per machine=$312,000/80,000=$3.9
variable manufacturing overhead per machine hour is $2.10
Predetermined overhead rate =$3.9+$2.1=$6
The last option is the correct one