Question

Two factory plants are making TV panels. Yesterday, Plant A produced 2000 panels. Two percent of the panels from Plant A and 7% 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 5%?

Answer 1

Let the number of panels produced by B be x.

Then :

The number of defective panels from B are :

7/100 × x = 0.07x

The number of defective panels from A are :

2/100 × 2000 = 40

Total defective panels are :

40 + 0.07x

Total panels manufactured is :

2000 + x

The overall percentage of the defective panels is 5%

Now linking the given information we have :

(40 + 0.07x) / (2000 + x) = 0.05

40 + 0.07x = (2000 + x) 0.05

40 + 0.07x = 100 + 0.05x

Collecting the like terms together :

0.07x - 0.05x = 100 - 40

0.02x = 60

x = 60/0.02

x = 3000

The panels produced by B is 3000.