Final answer:
The probability of a non-defective product coming from the second machine is 0.2730.
Step-by-step explanation:
To find the probability that a non-defective product came from the second machine, we need to consider the overall probability of selecting a product from each machine. The second machine produces 30% of the products, and the probability of a non-defective product from the second machine is 91% (100% - 9%).
Therefore, the probability that a non-defective product came from the second machine is the product of these two probabilities: 0.30 * 0.91 = 0.2730.
Rounding to four decimal places, the probability is 0.2730.