Answer:
0.3721 or 37.21%
Step-by-step explanation:
P(I) = 0.60; P(II) = 0.40;
P(not defective I) = 0.90; P(not defective II) = 0.80
The probability that the phone came from factory II, given that is not defective, is determined by the probability of a phone from factory II not being defective divided by the probability of a phone not being defective.
[tex]P(II|not) = \frac{P(II)*P(not_{II})}{P(II)*P(not_{II})+P(I)*P(not_{I})}\\P(II|not) = \frac{0.40*0.80}{0.40*0.80+0.60*0.90}\\ P(II|not) =0.3721 = 37.21\%[/tex]
The probability is 0.3721 or 37.21%.