Question: According to the National Restaurant Association, 20% of fine-dining restaurants have instituted policies restricting the use of cell phones ( Business Bulletin, The Wall Street Journal, June 1, 2000, p. A1). If you select a random sample of 100 fine-dining restaurants,
a. what is the probability that the sample has between 15% and 25% that have established policies restricting cell phone use?
b. the probability is 90% that the sample percentage will be contained within what symmetrical limits of the population percentage?
c. the probability is 95% that the sample percentage will be contained within what symmetrical limits of the population percentage?
d. Suppose that in January 2007, you selected a random sample of 100 fine-dining restaurants and found that 31 had policies restricting the use of cell phones. Do you think that the population percentage has changed?