Consider Exercise 5-21 and suppose that a cluster sample is chosen, where the randomly groups selected are (2) and (3). The total of all observations from group 2 is $7,100,000, while that from group 3 is $15,200,000.
(a) Estimate the mean spending and its standard error.
(b) Find a bound on the error of estimation using a 95% level of confidence.
(c) What are the disadvantages of using cluster samples in this situation?