In a recent year, a research organization found that 279 of the 427 respondents who reported earning less than $30,000 per year said they were social networking users. At the other end of the income scale, 316 of the 515 respondents reporting earnings of $75,000 or more were social networking users. Let any difference refer to subtracting high-income values from low-income values. Complete parts a through d below. Assume that any necessary assumptions and conditions are satisfied.

a) Find the proportions of each income group who are social networking users.

The proportion of the low-income group who are social networking users is:

The proportion of the high-income group who are social networking users is:

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 these proportions.