Many biographies are written in You can use friendly percents to find 35% of 80 by writing 35% as 25% + 10%. 25% of 80 is 80 divided by 4, which is 20. 10% of 80 is 80 divided by 10, which is 8. 20 + 8 = 28. So 35% of 80 is 28.

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.