A supermarket company has stores in 25 cities across the Middle East. The company wants to estimate the proportion of stores across the cities that do not meet a specified cleanliness criterion. The company decides to select a two-stage cluster sample containing one-half of the stores within each of four cities selected in the sample. The data collected are given in the following table. Estimate the proportion of stores not meeting the cleanliness criterion and place a bound on the error of estimation. City 1 234 Number of stores not meeting criterion 3 Number of store in the city Number of stores sampled 24 16 12 8 1 20 10 2 40 20 6