There were 845 million facebook users at the end of 2011, wich was up from 608 million users at the end of 2010.
51.5% of all users access facebook on mobile devices. how many users used mobile devices in 2011?

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.