Solving a percent mixture problem

Question

Two factory plants are making TV panels. Yesterday, Plant A produced twice as many panels as Plant B. Three 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 two plants together produced 900 defective panels?

Answer 1

Let PA = Plant A production. &. Let. PB = Plant B production.

PA = 2PB. (Given), For the defective. .03PA + .04PB = 900 = .03(2PB) + .04PB = 900

or. .1PB = 900. Then. PB = 9000. &. PA = 18,000