Answer with clear explanation

Aillianz a German CD manufacturer wants to diminish the size of the their CDS. So the start with a new production line. They know that the size of the CDs is normally distributed with a mean of 5 cm and a standard deviation of 0.4 cm (variance=(0.4cm)^2). If they examine a sample of 9 CDs and the size is measured what is the probability that the average size will be no more than 5.5 cm? 98.89 % 99.99% 77.77 % 91.79% Save