When dragons on planet Pern lay eggs, the eggs are either green or yellow. The biologists have observed over the years that 19% of the eggs are yellow, and the rest green. Next spring the lead scientist has permission to randomly select 63 of the dragon eggs to incubate. Consider all the possible samples of 63 dragon eggs. What is the mean number of yellow eggs in samples of 63 eggs? (that is the same as asking for the expected value of the number of yellow eggs)