Megamart collects is sales tax equal to 1/16 of the retail price of each purchase the tax is sent to the state government is the amount of tax collected to proportional to the cost of an item before tax is added? Explain.

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.