Patrick wanted to gather data about the cost of joining a community pool in his area. He plotted the data and determined that the average community pool membership cost consists of a one-time registration fee and a monthly fee modeled by the equation y = 15x + 40. Identify and interpret the y-intercept in this model.

According to a study conducted in 2015, 18% of shoppers said that they prefer to buy generic instead of name-brand products. suppose that in a recent sample of 1500 shoppers, 315 stated that they prefer to buy generic instead of name-brand products. at a 5% significance level, can you conclude that the proportion of all shoppers who currently prefer to buy generic instead of name-brand products is higher than .18? use both the p-value and the critical-value approaches.