Answer:
0.6154 or 61.54%
Step-by-step explanation:
Machine B output level= 80%
Machine A output level= 20%
Machine B defective rate = 0.04
Machine A defective rate = 0.10
The proportion of total washers that are defective is:
[tex]D=0.8*0.04+0.2*0.1\\D=0.052[/tex]
Therefore, the probability that a randomly selected washer was manufactured by machine B, given that it is defective, is determined by the proportion of defective washers produced by machine B divided by the proportion of total defective washers:
[tex]p=\frac{0.8*0.04}{0.052}\\p=0.6154=61.54\%[/tex]
The probability is 0.6154 or 61.54%.