Question

Two factory plants are making TV panels. Yesterday, Plant A produced panels. Seven percent of the panels from Plant A and 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 ?

Answer 1

1% of 4000 + 4% of B = 2% of (4000 + B)

 

40 + 0.04*B = 0.02( 4000 + B)

 

40 + 0.04* B = 80 + 0.02*B

 

40 + 0.04*B - 80 - 0.02B = 0

 

0.02*B - 40 = 0

 

0.02*B = 40

 

2B = 4000

 

B = 2000

 

 

CHECK:

     1% of 4000 + 4% of 2000 = 40 + 80 = 120 defectives

 

4000 + 2000 = 6000

 

120 out of 6000 = 120/6000 = 12/600 = 1/50 = 2%

 

Plant A produces 4000 panels and 1% of them , or 40, are defective.

Plant B produces 2000 panels and 4% of them,  or 80, are defective.