7. (Chapter 7) According to the National Center for Health Statistics, 22.4% of adults in the US. are smokers. Suppose random samples of 300 adults are obtained. a) What are the mean and the standard error of the sampling distribution of the sample proportion, 1'5 ? b) Would the shape of the sampling distribution of 1') be approximately normal? 0) What is the probability that out of a sample of 300 adults, we would nd that more than 28% of them are smokers