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| Question 1169525:  A previous survey shows that a machine making plastic components is correctly set
 up for the day's production on 85% of days. On days when it is set up correctly, 96%
 of the components produced are good. If the machine is not set up correctly, only 30%
 of the components produced are good. On a particular day, the machine is set up and
 the first component produced is found to be good. What is the probability that the
 machine is set up correctly?
 Found 2 solutions by  CPhill, ikleyn:
 Answer by CPhill(1987)
      (Show Source): 
You can put this solution on YOUR website! Let's break down this problem using Bayes' Theorem. **Define the Events**
 * **C:** The machine is set up correctly.
 * **G:** The first component produced is good.
 **Given Probabilities**
 * $P(C) = 0.85$ (Probability the machine is set up correctly)
 * $P(C') = 1 - P(C) = 1 - 0.85 = 0.15$ (Probability the machine is not set up correctly)
 * $P(G|C) = 0.96$ (Probability of a good component given the machine is set up correctly)
 * $P(G|C') = 0.30$ (Probability of a good component given the machine is not set up correctly)
 **We need to find:**
 * $P(C|G)$ (Probability the machine is set up correctly given the component is good)
 **Apply Bayes' Theorem**
 Bayes' Theorem states:
 $$P(C|G) = \frac{P(G|C) \cdot P(C)}{P(G)}$$
 Where $P(G)$ can be found using the law of total probability:
 $$P(G) = P(G|C) \cdot P(C) + P(G|C') \cdot P(C')$$
 **Calculations**
 1.  **Calculate $P(G)$:**
 $$P(G) = (0.96 \times 0.85) + (0.30 \times 0.15)$$
 $$P(G) = 0.816 + 0.045$$
 $$P(G) = 0.861$$
 2.  **Calculate $P(C|G)$:**
 $$P(C|G) = \frac{P(G|C) \cdot P(C)}{P(G)}$$
 $$P(C|G) = \frac{0.96 \times 0.85}{0.861}$$
 $$P(C|G) = \frac{0.816}{0.861}$$
 $$P(C|G) \approx 0.9477$$
 **Final Answer**
 The probability that the machine is set up correctly given that the first component produced is good is approximately 0.9477.
 
Answer by ikleyn(52879)
      (Show Source): 
You can put this solution on YOUR website! . A previous survey shows that a machine making plastic components is correctly set
 up for the day's production on 85% of days. On days when it is set up correctly, 96%
 of the components produced are good. If the machine is not set up correctly, only 30%
 of the components produced are good. On a particular day, the machine is set up and
 the first component produced is found to be good. What is the probability that the
 machine is set up correctly?
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 
 The problem's formulation in the post is INCORRECT.
 In this formulation, the problem can not be solved/answered.
 
 To be correct, it should be re-formulated, re-edited and re-written
 from scratch.
 
 By reading this problem formulation, I clearly see that a person
 who created it is mathematically incompetent in the subject.
 
 
 The "solution" in the post by the other tutor @CPhill is GIBBERISH
 produced by an undertrained artificial intelligence.
 
 To keep you mind in safe condition, I recommend you to ignore
 both the problem and its quasi-"solution" produced by @CPhill.
 
 
 \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
 
 
 Regarding the post by @CPhill . . .
 
 
 Keep in mind that @CPhill is a pseudonym for the Google artificial intelligence.
 
 The artificial intelligence is like a baby now. It is in the experimental stage
 of development and can make mistakes and produce nonsense without any embarrassment.
 
 
 It has no feeling of shame - it is shameless.
 
 
 This time, again,  it made an error.
 
 
 Although the @CPhill' solution are copy-paste  Google  AI solutions,  there is one essential difference.
 
 Every time,  Google  AI  makes a note at the end of its solutions that  Google  AI  is experimental
 and can make errors/mistakes.
 
 All @CPhill' solutions are copy-paste of  Google  AI  solutions, with one difference:
 @PChill never makes this notice and never says that his solutions are copy-past that of Google.
 So, he NEVER SAYS TRUTH.
 
 Every time,  @CPhill embarrassed to tell the truth.
 But I am not embarrassing to tell the truth,  as it is my duty at this forum.
 
 
 And the last my comment.
 
 When you obtain such posts from @CPhill,  remember,  that  NOBODY  is responsible for their correctness,
 until the specialists and experts will check and confirm their correctness.
 
 Without it,  their reliability is  ZERO and their creadability is  ZERO,  too.
 
 
 
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