Greatest president ~ A Gallup Poll of American adults in February 2009 asked the following question. "Which of the following pre
sidents would you regard as the greatest: Washington, Franklin Roosevelt, Lincoln, Kennedy, or Reagan?" The order of the presidents was rotated to avoid bias. Based on the sample, a 95% confidence interval for the actual proportion American adults who choose Lincoln as the greatest is given by (0.1759, 0.2204). What is the sample proportion? Give the exact answer as a decimal.
A confidence interval has two bounds, a lower bound and an upper bound. The sample proportion is the halfway point between these two bounds, that is, the sum of the bounds divided by 2.
