Markets have become interested in the potential of social networking sites. But they need to understand the demographics of social networking users. Pew Research has conducted surveys since 2012 that address these questions.

(www.pewinternet.org/Reports/2013/Social-mediausers/

Social-Networking-Site-Users). In late 2012, the Pew Research survey found that 525 of 846 surveyed male Internet users use social networking. By contrast 679 of 956 female Internet users use social networking.

a) Find the proportions of male and female Internet users who said they use social networking.

b) What is the difference in proportions?

c) What is the standard error of the difference?

d) Find a 95% confidence interval for the difference between the proportions.