Bob purchased a prepaid phone card for $15. long distance calls cost 18 cents a minute using this card. bob used his card only once to make a long distance call. if the remaining credit on her card is $12.30, how many minutes did her call last?

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.