If xy = 1, which is equivalent to x(x – 1)(y + 1)?
a) x – 1
b) x2 – 1
c) x2 – x
d) x2 – x + y – 1

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.