1. The percentage of defective articles produced by a machine is 8%. Use a suitable approximation and calculate: a) The probability that in a random sample of 20 articles, more than 13 will be defective. b) The probability that in a random sample of 400 articles, between 30 and 50 (inclusive) articles will be defective. Remember to state all the conditions that need to be satisfied in order to use an appropriate approximation