lets say that plant A produced 100 panels, so plant B produced 50 panels, now because 5% of the panels that each plant produces is defective, Plant A produced 80 working TV panels and 20 defective TV panels. Plant B produced 40 working TV panels and 10 defective TV panels.
if both plants are counted together with plant A having produced 100 panels and plant B having produced 50 panels they will have produced 150 TV panels only 135 of the 150 TV panels would work. 15 panels would be faulty.
if you take the number of faulty TV panels without counting the plants together, of the 150 TV panels produced 30 would be faulty.
