A new product is launched in two cities, Chillan and Talca, in the south of the country. Advertising in Chillan is based almost entirely on television, while in Talca it is spent on a balanced mix of television, radio and newspapers. After a month, a survey is carried out to determine the awareness of the product, and the following results are obtained:
They squeal
People surveyed 608
People with knowledge 392
Talca
People surveyed 527
People with knowledge 413
Determine a 95% confidence interval for the regional difference for all consumers who are aware of the product.