26. Four workers work in a small factory assembling chairs in which of them respectively assembles 30%, 30%, 20%, and 20% of the chairs. From the past record, it is know that each of the workers are...

Extracted text: 26. Four workers work in a small factory assembling chairs in which of them respectively assembles 30%, 30%, 20%, and 20% of the chairs. From the past record, it is know that each of the workers are responsible for 7%, 5%, 3%, and 2% of defective chairs, respectively. Suppose that a chair is chosen at random, what is the probability that the chair is defective? (a) 0.021 (c) 0.042 (b) 0.036 (d) 0.046