A city consists of a total of two million residents and is divided into three boroughs that have 750,000, 900,000 and 350,000 residents, respectively. The city council is considering building a new baseball stadium. If the project is undertaken, it will be financed by an increase in taxes. In order to determine how the city feels about the new stadium, independent random sampler of 500 adults from each borough were taken. The numbers in favor of the stadium were found to be 325, 201, and 400, respectively.

(a) Using an unbiased estimation procedure, find an estimate of all adults in the city who favor the stadium.

(b) Find a 90 % confidence interval for this population proportion.