An April 2009 survey of 2253 American adults conducted by the Pew Research Center’s Internet & American Life Project revealed that 1262 of the respondents had at some point used wireless means for online access.

a. Calculate and interpret a 95% CI for the proportion of all American adults who at the time of the survey had used wireless means for online access.

b. What sample size is required if the desired width of the 95% CI is to be at most .04, irrespective of the sample results?

c. Does the upper limit of the interval in

(a) specify a 95%

upper confidence bound for the proportion being estimated? Explain.