6. The distribution of the weight of a prepackaged "1-kilo pack" of cheddar cheese is assumed to be N(1.18, 0.072), and the distribution of the weight of a prepackaged "3-kilo pack" of cheese (special for cheese lovers) is N(3.22, 0.092). Select at random three 1-kilo packs of cheese, independently, with weights being X1, X2 and X3 respectively. Also randomly select one 3-kilo pack of cheese with weight being W. Let Y = X1 + X2+ X3- (a) Find the mof of Y. (b) Find the distribution of Y, the total weight of the three 1-kilo packs of cheese selected. (c) Find the probability P(Y