Estimating Proportions

Does anyone know any good sites fro explaining estimating proportions? I am clueless as to how to do this. My notes are not helping me. Is there a way to do the calculations with a TI-83 Plus?

The American Heart Association is conducting an ad campaign. The Association wants to know the fraction of American smokers over the age of 21.

Suppose a sample of 292 Americans is drawn. Out of these people 243 do not smoke. Using the data estimate the proportion of Americans over 21 who smoke.
Well if the sample can be thought of as a representative sample from all Americans over 21. Then the estimated proportion of Americans over 21 who smoke is:

(number in sample who smoke) / (total in sample) = (292-243) / 292= 0.168

We can calculate the 95% confidence interval for the ratio.

SE = sqrt[p(1-p)/N] = sqrt(0.168*0.832/292) = 0.02188

95% confidence interval = 0.168 +/- 1.96 SE = 0.125 to 0.211