Amajor retail clothing store is interested in estimating the difference in mean monthly purchases by customers who use the store's in-house credit card versus using a visa, mastercard, or one of the other major credit cards. to do this, it has randomly selected a sample of customers who have made one or more purchases with each of the types of credit cards. the following represents the results of the sampling based on these sample data, what is the lower limit for the 95 percent confidence interval estimate for the difference between population means? group of answer choices