The sample taken is a simple random sample (srs) so is representative of the population as a whole. If 1139 out of the 1201 Americans sampled were found to live in neighborhoods with acceptable levels of carbon monoxide, then we estimate the proportion `p` of Americans who live in neighborhoods with acceptable levels of carbon monoxide to be `hat(p) = 1139/1201 = 0.948` to 3 significant figures. This is called a "point estimate" because we are providing one estimated value, rather than an estimated value and an interval, say a confidence interval.

A point estimate for the proportion of American's living in acceptably low CO neighborhoods is 0.948