Solving a percent mixture problem using a linear equation

Question

Two factory plants are making TV panels. Plant A produced 15,000 panels. 10% of the panels from Plant A and 3% 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 8%?

Answer 1

Let B represent the number of panels produced by Plant B. That means the total produced by the two plants is 15,000 + B.

From the conditions given, we know that (.1)(15,000) + (.03)B = (.08)(15,000+B)

Consolidating terms, (.1 - .08)(15,000) = (.08 -.03)B

Simplifying, (.02)(15,000) = (.05)B

B = 300/.05 = 6000