Consider each situation described. Identify the population and the sample, explain what p and p̂ represent, and tell whether the methods of this chapter can be used to create a confidence interval.
a) A consumer group hoping to assess customer experiences with auto dealers surveys 167 people who recently bought new cars; 3% of them expressed dissatisfaction with the salesperson.
b) What percent of college students have cell phones? 2883 students were asked as they entered a football stadium, and 2430 said they had phones with them.
c) Two hundred forty potato plants in a field in Maine are randomly checked, and only 7 show signs of blight. How severe is the blight problem for the U.S. potato industry?
d) Twelve of the 309 employees of a small company suffered an injury on the job last year. What can the company expect in future years?