Answer
$(67.5,72.5)$
Work Step by Step
The standard deviation is not given in this problem, so we must use a confidence interval program that does not involve standard deviation. Thus, we first must find the number of people who answered yes:
$= .7 \times 1501 = 1051$
Plugging this, as well as the population size of 241 million Americans, into a confidence interval calculator, we find that the lower limit is $=70-2.5=67.5$ and that the upper limit is $=70+2.5=72.5$. This is our 95 percent confidence interval.
