Two factory plants are making TV panels. Yesterday, Plant A produced 8000 panels. One percent of the panels from Plant A and 4% of the panels from Plant B were defective. How many panels did Plant B produce, if the overall percentage of defective panels from the two plants was 3%?

8000 from plant A with 1% defective

x from plant B with 4% defective

8000 + x = y with 3% defective

da/a = 0.01 - > 80 = da

db/b = 0.04 - > db = 0.04b

(da+db) / (a+b) = 0.03

(80+b*0.04) / (8000+b) = 0.03

80+b*0.04 = 0.03 * (8000+b)

80+b*0.04 = 240 + 0.03b

80 - 240 = 0.03b - b*0.04

-160 = - 0.01b

b = 160/0.01

b = 16000

the panels from the plant b were 16000