Please provide steps and explanations

1)

Boxes are labeled as containing 500 g of cereal. The machine lling the boxes produces weights that are normally distributed with standard deviation 12 g. (a) If the target weight is 500 g, what is the probability that the machine produces a box with less than 4-80 g of cereal? (b) Suppose a law states that no more than 5% of a manufacturer's cereal boxes can contain less than the stated weight of 500 g. At what target weight should the manufacturer set its lling machine in order to comply with this regulation