3. Given three identical boxes I, II, III each containing two coins. In box I, both coins are gold, in box II both are silver coins and in box III, there are one gold and one silver coin. A person chooses a box for a coin. If the selected coin is gold, what is the probability that the other coin in the box is also gold coin? 4. In a factory which manufactures bolts, machines A, B and C manufacture 25%, 35 % and 40 % of the bolts. Of their outputs, 5, 4, and 2 percent are respectively defective bolts. A bolt is drawn at random from the product and is found to be defective. What is the probability it is manufactured by Machine C