Social log-ins involve recommending or sharing an article that you read online. According to Janrain ("T. Wayne, One Log-In Catches on for Many Sites," The New York Times, May 2, 2011, p. B2), in the first quarter of 2011, 35% signed in via Facebook compared with 31% for Google.
If a sample of 10 social log-ins is selected, what is the probability that
a. More than 4 signed in using Facebook?
b. More than 4 signed in using Google?
c. None signed in using Facebook?
d. What assumptions did you have to make to answer (a) through (c)?