Suppose the random variable X is normally distributed with mean 56 and standard deviation 10. Let Z be distributed acording to the standard normal distribution. Then P(X< 72.7) is the same
as
P(Z <

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.