For each situation below identify the population and the sample and explain what p and p represent and what the value of p is. Would you trust a confidence interval for the true proportion based on these data? Explain briefly why or why not.
a) A marketing analyst conducts a large survey of her customers to find out how much money they plan to spend at the company website in the next 6 months. The average amount reported from the 534 respondents is $145.34.
b) A campus survey on a large campus (40,000 students) is trying to find out whether students approve of a new parking policy allowing students to park in previously inaccessible parking lots, but for a small fee. Surveys are sent out by mail and e-mail to all students. Of the 243 surveys returned, 134 are in favor of the change.
c) The human resources department of a large Fortune 100 company wants to find out how many employees would take advantage of an on-site day care facility. They send out an e-mail to 500 employees and receive responses from 450 of them. Of those responding, 75 say that they would take advantage of such a facility.