If a certain machine makes electrical resistors having a mean resistance of 60 ohms and a standard deviation of 4.5 ohms, what is the probability that a random sample of 81 of these resistors will have a combined resistance of more than 4949.1 ohms?

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.