Answer:
A) 14.72 hours
B) An additional worker should be hired since the lost work time is 14.72 hours
Step-by-step explanation:
Number of machines on manufacturing line = 8 
percentage of machine been down = 23% 
number of workers capable of running and repairing machines = 2
machine productivity ( per machine ) = 18 units/hour
overhead cost / machine = $713 
hourly rate paid per worker = $15 
Total number of work hours = 8 hour
A) calculate Total amount of lost worktime
 = number of machines * Total number of work hours * 23%
 = 8 * 8 * 23% = 14.72 hours 
B) An additional worker should be hired since the lost work time is 14.72 hours