Stan's lawn mower had 1/8 of a gallon of gasoline in the tank. After he mowed, 1/4 of a gallon was left in the tank. What was the total amount of gasoline stan used

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.