7 Bags of sugar are packed in boxes, each box containing 20 bags. The masses of the boxes, when empty, are normally distributed with mean 0.4 kg and standard deviation 0.01 kg . The masses of the bags are normally distributed with mean 1.02 kg and standard deviation 0.03 kg .

1. Find the probability that the total mass of a full box of 20 bags is less than 20.6 kg .
2. Two full boxes are chosen at random. Find the probability that they differ in mass by less than 0.02 kg .