Answer:
84%.
Explanation:
A task consumes 4 minutes
21 tasks consumes = 21 task * 4 minutes = 84 minutes
No of Workstation = 5
Cycle time = 20
Efficiency = Total task time / (Cycle time * Number of workstations)
Efficiency = 84 /(20*5)
Efficiency = 84 / 100
Efficiency = 0.84
Efficiency = 84%
Thus, the efficiency of this line is 84%.