According to the Pew Research Internet Project (Dec. 2013) survey, the two most popular social networking sites in the United States are Facebook and LinkedIn. Of all adult Internet users, 71% have a Facebook account, 22% have a LinkedIn account, and 18% visit both Facebook and LinkedIn.

a. Draw a Venn diagram to illustrate the use of social networking sites in the United States.

b. Find the probability that an adult Internet user visits either Facebook or LinkedIn.

c. Use your answer to part b to find the probability that an adult Internet user does not have an account with either social networking site?