$2-)$ A company has three factories A$,$ B$,$ C making $20\%,70\%$ and $10\%$ of its out put respectively. The percentages of articles made by $A,B,C$ that are defective are $10\%,20\%,30\%$ respectively. An article is chosen at random from stock and is found to be defective. Find the probability that it came from factory $C$ or $A.$