Rosa works in an office building with many floors. for her office, she goes down 2 floors for a meeting. then, she goes up 7 floors to have lunch. after lunch, she goes down 15 floors to the first floor. what floor is rosa's office on?

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.