According to the Pew 2012 News Consumption survey, 50% of adults who post news on Twitter (“tweet”) are younger than 30. But according to the U.S. Census, only 23% of adults are less than 30 years old. A separate survey by Pew in 2012 found that 15% of adults tweet.
a) Find the probability that a random adult is both less than 30 years old and a Twitter poster. That is, find P(Tweet and <30).
b) For a random young (<30) adult, what is the probability he or she is a tweeter? That is, find P(Tweet| <30) (Hint: use Bayes theorem.)